Have you ever felt like you try and try and try, but just can’t get the traction to make forward progress on your Mazdaspeed 3 car build? Ya, it happens to the best of us and the 2022 season was my time…both in literal traction and life.
If you haven’t seen my build yet, the @halfmilespeed3, go check it out. It’s an awesome combo of DIY, Teamwork, Innovations, and CorkSport goodies you all love.
Back to this traction conundrum. Racing an 800+hp FWD Mazdaspeed 3 on small airport airstrips with no prep and plenty of dust has proven to be challenging. There have been many successes and many challenges, but ultimately it comes down to those two tiny patches of rubber that meet the road.
LITERALLY NO TRACTION
Yes, Motec helped substantially with traction control and Justin’s ramp-up in power delivery also helps, but really…I just didn’t have any damn traction. Sticky tires with meaty sidewalls also help, but again traction was such an issue! There had to be a better way!
Wheel & Tire Setup:
Front: Toyo TQ 255/50 on 16×8+38
Rear: Toyo R888R 255/40 on 17×9+45
And there was and I had been talking about the idea for a year or so already. Then life happened.
As you can see with the racecar; I like to go fast. I carried that enthusiasm into my love of mountain biking one day in June 2022 and well…I got a lesson in physics let me tell you.
Five broken ribs, a double punctured lung, level 3 AC separation, and a fractured collar bone and scapula. Resulting in weeks of hospital stays and three surgeries; then months of recovery and physical therapy. Let’s just say the 2022 season did not go as planned.
But it did get me focused on solving my traction problems…
Mazdaspeed 3 with CorkSport Mazda Performance Parts Back (AKA HalfMileSpeed3)
The Goal…Mazdaspeed 3 AWD Swap
So I decided it was time to stop talking about it and actually take action (well as soon as I physically could that is). I made a plan and figured out the details and order of operations to finally get my traction back.
While I am not the first to do a Mazdaspeed AWD swap. I did have a goal to make my build unique in the sense that the AWD swap is catered to racing performance. Meaning the strength of custom parts and the rear suspension design and the new fuel system are capable of handling the 4-digit horsepower goal I have and the abuse of racing.
Talking horsepower…what does the car make right now?
This is at a modest 40-41psi using a Xona Rotor 9569s with the X3C compressor housing and 1.03A/R turbine housing. Later Justin @freektune and I turned it up a bit more to see how close we can get to the 600wtq threshold and hold it. Clipping off an 881whp run…damn! This was supported by the many CorkSport Mazda performance parts you can get for your Mazdaspeed as well. From engine mounts to manifolds, anything that isn’t a one-off custom is CS.
Anyways…I have since updated the compressor wheel to a 99 lb/min design compared to the above 95 lb/min design and a larger compressor housing which is more efficient. This setup has not been dyno tested yet, but talking to the engineers at Xona…2023 is going to be spicy!
Close up because who doesn’t like billet turbo shots!?
Dare I say this is the largest turbo in the stock location ever on a Mazdaspeed? Go ahead…prove me wrong. To compare, this competes with a Precision 6870.
The Start of the Mazdaspeed 3 AWD Swap
Anyways, this is the introduction to my Mazdaspeed 3 AWD swap here at CorkSport HQ. I actually started the swap in October 2022 and have been making big steps each month. We are going to be sharing blog updates rapidly as I wrap up the swap over the next couple of months.
There will be much more technical info and images coming up so grab a drink and enjoy!
You can also find updates on my IG @halfmilespeed3, the CorkSport 7th Gear Membership, and on mazdaspeeds.org.
The time has FINALLY come…years in the making! Thousands of hours have gone into the development of the only turnkey turbocharger kit for the Mazda 3. From air filter to downpipe and everything in between, the Turbo Kit for the 3rd generation Mazda 3 has finally come full circle and IT IS AWESOME!
Are you ready for an extra 115-125whp and 80-90wtq?
Many have asked “Why So Long?” and the truth is because we, the Team at CorkSport, would not allow ourselves to put out a kit that was not complete, was not turnkey, and was not proven to be daily and track ready. We have put thousands of miles on out test vehicles; both on the track…
Boosted Mazda 3 TC America Race Car
And on the street…
Boosted Mazda 3 Street Test Mule with Turbo Kit
So what is involved in developing a turnkey turbo kit for the originally naturally aspirated vehicle? Well, basically everything., Let’s get more into the details.
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The turbo is a big one, spec’ing the size, style, & location is a significant aspect of the kit. In fact, we tested multiple sizes before deciding on the turbo for the kit. Finding the right balance of spool/response, boost operating pressure, and even sound was a consideration (hey we all like turbo noises right?) With that we are using an MHI based turbo that utilizes journal bearings and liquid cooled CHRA. Our current CST4 and CST5 turbochargers for the Mazdaspeed use the same MHI CHRA and have proven very reliable and robust.
The turbo in the Mazda 3 Kit is also uniquely a twin-scroll internally wastegated design. This helped with spool and response while using a larger wheel spec and the internal wastegate keeps overall costs down and quiet.
On each end of the turbo is the next major design challenge, the exhaust manifold and downpipe. Now, in most kits you would expect to see a fabricated manifold and downpipe. While that is not necessarily bad, there are more robust methods of manufacturing that can perform equal if not better. This method is casting, which is what we have done. The exhaust manifold is a cast stainless steel 304 twin-scroll design. This one-piece design means there are no welds, seams or connections that could fail and the wall thickness is thicker (5mm vs 3mm) when compared to standard fabricated manifolds.
The downpipe utilizes a cast bellmouth which is then welded to a 3-inch pipe and flex section. This downpipe then aligns with the OEM location exhaust so you can run a stock exhaust (don’t be silly though), a 60mm or 80mm exhaust with your turbo kit.
Since we are talking about the cat-back exhaust let us just say that for peak performance you will want the 80mm exhaust system on your Mazda 3. Moving down to the 60mm you will lose a tad bit of power. Note: In the instructions there are specific boost controller settings for each exhaust setup.
Now we have all the plumbing to get that boost from the turbo to the engine. When we approached this we wanted a kit that was stupidly simple and clean in the engine bay. The result was ONLY two pieces of charge piping and four pieces of charge piping silicone. This keeps the possible boost leaks to a minimum and the install process simple. With that being said, the “hotside” charge piping runs alongside the passenger side of the engine and the “coldside” runs right up from the intercooler and to the throttle body.
To complete the charge air system we have the intercooler. The intercooler is no off-the-shelf generic unit either, we custom designed the cast aluminum endtanks to fit with the Mazda 3 chassis WITHOUT cutting and maximized the intercooler size to perform great with the power goals of the Turbo Kit, again without cutting your Mazda 3. Good to 400 horsepower, the intercooler will easily cover the current power and future growth in power of the kit for quite some time.
Because of the custom fit and lack of cutting, the intercooler nearly disappears in the OEM bumper for a stealth look. The black finish performs and looks great through the seasons. If you want to a customized stand out look, you could paint the core a nice bright silver finish without issue.
So we’ve covered the obvious parts of a “turbo kit” but what makes the kit turnkey? It’s the little things, like clamps, hardware, and connection like the turbo cooling, and the oil feed and oil drain. For the oil feed and drain we have provided perfect length stainless steel braided lines and all the needed fittings. The oil drain is extra special because on a non-factory turbo there is NO spot for the oil drain in the engine. So install of requiring you to drill a hole in your oil pan and risk causing a leak, we do the work for you with a new OEM oil pan. We complete the drilling, the drain fitting install and sealing. All you have to do is remove your oil pan and install the new oil pan with the drain fitting installed.
Lastly, to make all the big parts fit in the engine bay and look good, we had to create some clearance for the intake by using a smaller AGM battery vs the huge lead acid battery. To do that we designed a SS battery mount and ECU relocation bracket along with a new 550ca/450cca AGM motorsport battery which is included for ground shipping customers. If you are international and the kit has to air ship to you then you will need to source the battery locally.
Now to really round off the “turnkey” aspect of the kit we have the boost control system which includes a TurboSmart E-Boost controller which allows us to dictate and control the boost curve for optimal power delivery and reliability. No manual boost controller here that does whatever it wants. To monitor boost we provide a CorkSport boost gauge that you can mount anywhere inside the cabin for easy readout. Also, with a boosted setup and high compression ratio a set of 1-step colder spark plugs are required for safe operation, these are also included and future replacements can be purchased at CorkSport.
Most important is the tuning, and this is where we have spent hundreds of hours alone getting the car to perform consistently and reliably for you. The turbo kit had to feel fun, fast, and repeatable all while being safe to drive every day on a stock engine. With the CorkSport Turbo Kit, you will get a calibration license to your vehicle and Mazdaedit license designed to operate on premium grade gasoline (91-93octane).
Now to the numbers you want to know about! POWER like you’ve never seen from a 3rd Gen Mazda 3 with the Turbo Kit. Many said the high compression Sky-Activ couldn’t handle boost…many said they are “glass” engines”…we are here to tell you they are wrong.
How about 9.5psi of boost and gains of 115-125whp/80-90wtq? All on the stock fuel system and simple premium pump gas?
In this dynograph you can see four dyno runs. The two lower runs are from our 2018 Mazda 3 2.5L MT. This is a 100% stock car with no tuning changes. The much nicer two runs are the final result of 9.5psi for the CorkSport Turbo Kit.
Power is not just about a peak number, power (and a resulting fast/fun car) is about the power under the curve. Our goal was to develop a kit that made a fast and fun car throughout the rpm range of the 2.5L SkyActiv. With a huge increase in torque across the rpm range, you have a car that will be fun from 3500rpm to 6000rpm before power starts to fall off. This is the 3rd Generation Mazdaspeed that Mazda never gave us.
How does the powertrain handle this? We have only used OEM stock engines, clutches, and manual transmissions in our in-house testing. This goes for our street can and track-only racecar.
However, our in-house testing has been successful with OEM components, our beta tester did have an OEM clutch slippage early on in their testing. Our review of the clutch and the history of the clutch showed us that we are at the limit of the clutch. If the clutch has lots of wear and tear it may not last long with the added torque from the turbo kit. Therefore we cannot guarantee the successful ability to use the OEM clutch equipped in your Mazda.
With that being said there are options on the market for performance clutches that are either available now or are in development. We are personally working with X-Clutch to develop a performance clutch for the community.
Let’s wrap this up…the most complete and ready-to-run turbo kit available for your 2.5L MT Mazda 3. You can make power with easily accessible pump gas up in the 280+whp range and enjoy the daily drive and track. There will not be any surprise runs to the hardware store, as long as you have some wiring supplies, and you could get this done over a long weekend with a buddy that knows how to wrench.
Speaking of the install, the kit can be completed in a long weekend. If you work diligently we’d say 2-3 days to get it done. Follow the color step-by-step online PDF instructions and review the youtube video install before you get started to have the best success.
We also have a specific video for the TurboSmart E-Boost controller setup so you know you get it setup just right. While this project can seem daunting at first, we promise it all comes together if you follow the detailed instructions.
What’s this going to cost you? Less than you expect to be honest. Look at the ND Miata Turbocharger/Supercharger Kits and you would have a good idea of what it should cost, but really we want the community to get this kit and enjoy it so we’ve worked hard to provide the most value for the price on the Turbo Kit.
Thank you for taking the time to read about our Turbo Kit for the 3rd Gen Mazda 3 & Mazda 6. We are SOOOO excited to finally bring this to the community and for everyone to have the opportunity to take their Mazda 3 2.5L to the next level.
For the last four years, we’ve been asked countless times if the CST4 Mazdaspeed Turbo is a direct replacement for the OEM K04 Turbo. With the number of cars experiencing their 2nd, 3rd or even 4th owner, this question is being asked more frequently. While CorkSport’s intent is to freely share information across the Mazda community, we cannot be everywhere all at once, and we will most likely miss the exact moment the debate explodes on your favorite Facebook page. For that reason…
Today, we’re setting the record straight: The CST4 Turbo for the Mazdaspeed 3 is a drop-in UPGRADE from the ground up, and by no means is it an apples-to-apples comparison with the asthmatic Mazdaspeed K04 turbo.
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How Does It Work?
Before we dive into the dirty details, you might be craving more details on how a turbo works? You are in luck! Check out our white paper on the CST4 and what makes up the anatomy of a turbocharger, bone up on the importance of a “bolt-on” vs a “drop-in” turbocharger, learn the difference between an internal vs external wastegate and finally why the turbine wheel design/materials make a difference. Now let’s get back to what this means for the CST4 and K04.
Is The CST4 Reliable?
The CST4 Mazdaspeed turbo continues to prove itself as one of the best bolt-on options coupled with the needed reliability to withstand the additional demands of chasing 400 WHP – something the KO4 cannot accomplish. This is due to an upgraded center housing rotating assembly (CHRA) which has a larger center shaft and larger bearings than the OEM turbo. The CorkSport turbo also sports a performance journal bearing with a full 360° thrust collar, which is what allows the turbine shaft and compressor to spin freely. The OEM K04 turbo comes standard with a limited 270° thrust collar.
Does The CST4 Have Increased Airflow Over The K04?
Next comes wheels, which is where the CST4 really shines. As shown in the image above, we have the CST4 on the left and the OEM K04 on the right. The CST4 is 12% larger on the compressor inducer, and 21% larger on the exducer than the OEM K04. Combined with the use of a taller wheel (green line), every revolution of the CST4 not only brings in a greater quantity of air into the compressor but has a higher airflow capacity, thus moving a greater volume of air. For those of you that need a few more key specific numbers; The OEM K04 uses a 45mm inducer; 56.25mm exducer cast compressor wheel, while the CST4 uses a 50.5mm inducer and 68.1mm exducer forged billet compressor wheel.
On the turbine side, the OEM K04 turbo uses a 50.1mm inducer and a 44.5mm exducer 12-blade cast wheel. The CST4 turbo uses a 56.2mm inducer and 49mm exducer high-flow 9-blade design. Again, the CST4 outshines the K04 with the turbine inducer being 12% larger and the exducer 10% larger. The 9-blade design has two key benefits: more peak exhaust flow as there is less material in the way of flow, and 21% lighter for a faster spool time.
The final component is the compressor and turbine housings. The K04 turbo uses restrictive housings that cannot keep up at higher RPMs, and especially at higher boost levels. You can feel this as your stock turbo “runs out of steam” up above ~5200 RPM. The CST4 turbo housings may fit exactly in the OEM locations and use the OEM hook up points but that is where the similarities end.
Both the compressor and turbine housings were increased in size, increased in A/R, and optimized for the stock inlet and outlet sizes to provide better top-end capabilities. The compressor ended up at 0.53 A/R, while the turbine ended up at 0.66 A/R. This combo of housing and wheels keeps power all the way to redline, and in initial testing showed a 50WHP gain at the same boost pressure.
How Much Power Does The CST4 Make?
So what does all of this mean in terms of power? We’ve seen the OEM K04 pushed way out of its comfort zone and make in the 350-360WHP range with the right supporting mods. This is far out of the efficiency range of the little K04, and it’s a ticking time bomb when running at this power level. The CST4 turbo, on the other hand, is perfectly happy running in the 400WHP range all day, again, with the right supporting mods. We’ve even seen it pushed to its limit in the 450-460 range.
For those of you more interested in boost pressures, the K04 can hit a max of ~24-25psi in the midrange before it’s out of its efficiency range and starts producing just heat. At redline, the Mazdaspeed K04 is typically at a max of about 17-18psi. What you feel as your car seems to stop accelerating after ~5200RPM on the stock turbo. The CST4 does a lot better, hitting a max of ~29-30psi in the midrange but carries the high pressure into higher RPMs, with peak boost pressure at redline of ~26-27psi. This keeps you pushed into your seat with a smile on your face!
How Quickly Does The CST4 Spool?
We get a lot of questions on how fast this turbo spools, so let’s take a moment to discuss both. The Mazdaspeed OEM K04 spools very quickly since its housings and wheels are so small. If tuned incorrectly it can spool almost instantly and kill blocks with an extremely low-RPM torque spike. The CST4 also spools quickly, making full boost by approximately 3300RPM on most cars. The big difference is that the CST4 carries power out to redline instead of falling off as the K04 does. To be clear, you still have to be careful with the CST4 as it too can kill a stock block with too aggressive of a tune.
Is The CST4 A Drop-In?
So bringing things full circle, the “drop-in” aspect of the CST4 means you can run it with almost no other supporting parts, only a HPFP upgrade, access port, and a tune are required. It also means that it hooks up directly to the OEM inlet and outlet flanges so that there are no excessive modifications required to make the turbo fit your Mazdaspeed. We even include new studs, lock nuts, gaskets, a custom upper coolant line, new coolant and oil crush washers, and the correct oil feed banjo bolt so there is no hassle of finding replacement hardware, gaskets, or lines to make your turbo function. We strongly recommend picking up a CorkSport EBCS to best control the boost on your CST4 Turbo. We have also found that the stock intake size will be maxed out at around 18-19psi on the CST4. To get more power from there, a 3 inch or 3.5-inch intake will be needed.
By no means is the CST4 a K04 since it’s larger and has much higher horsepower capabilities. For those of you more familiar with Garett turbos, the CST4 is just a smidge bigger than a GTX2867.
If you want even more info on what makes the CST4 tick be sure to check out the white paper on the subject HERE. As a final afterthought, remember that the CST4 is getting an EWG housing option in the coming months, for added features (and noise!) that just don’t come with the K04. Stay tuned for that, and be sure to ask any questions you may have.
We hear this alot as the Mazdaspeed platform continues to grow and the 450-500whp build becomes the status quo. Following up the EWG Housing Design & Details Blog about the new CorkSport EWG Housing, we want to share some testing data and differences we saw between an IWG (internal wastegate) and EWG (external wastegate) setups.
Details about design, flow, placement, data, and feedback from our CST4 EWG Beta Tester.
IWG vs. EWG on the CST4
Let’s jump right in! First up is a spring pressure comparison between the IWG and EWG housing on a CST4 turbocharger. Let’s first define what “spring” pressure is: this is the resulting boost pressure with 0 added wastegate duty cycle. AKA we are not trying to add boost pressure.
Immediately you can see some very obvious differences. The IWG setup has a taper up boost curve that could be considered boost creep. Some boost creep is ok, but an excessive amount may reach the capacity of the fuel system or other systems in the vehicle. In this setup that is not the case, but it does show that the IWG is at its limits for boost control.
With the EWG setup you see a much different curve. The boost builds a few hundred RPM later (due to the larger 0.82 A/R) then climbs right to the spring pressure and then settles to a consistent plateau; very predictable and controllable.
CorkSport EWG and IWG Designs
Now let’s look at the design to better understand why. On the left is the EWG turbine housing with a 0.82 A/R and on the right is the IWG turbine housing also with a 0.82 A/R (we don’t want the A/R to be a factor in this review).
The EWG housing has a very efficient flow path for the exhaust gas to reach the EWG control valve along with a much larger path to flow. Both of these features provide excellent flow and thus control of boost pressure.
The IWG housing uses a side port in the turbine scroll to exhaust gas. In this setup, the exhaust gas must make an abrupt turn and pass through a much smaller port. Both of these issues reduce boost control.
Here is a diagram showing placement of an EWG in the exhaust pre-turbine. Granted we are comparing a EWG and IWG, but the concept of flow is the same.
Exhaust gases will always take the path of least resistance and if the turbine wheel is the easier path than the wastegate then boost control will be more difficult.
(Left) Internal Wastegate Setup | Common Issues (Right) External Wastegate Setup | Optimized Setup Click to Expand
This graph was shown in the last blog, but we want to show it again so you can directly compare it to the data graph below.
Below is the boost curves for the CST5 in both IWG and EWG setup. Alone each graph actually looks really good, but when overlaid you can see some interesting differences.
IWG vs. EWG on the CST5
The purple IWG graph has a crisp spool and then flat-lines at approximately 30psi with a slight fall off at 6500rpm. The CST5 IWG setup does control boost really well, but holding the turbo back at spool up and not over-boosting or spiking was a small challenge. An abrupt boost curve like this can make the car somewhat difficult to drive because the torque “hits” very hard and you lose traction.
The EWG setup was a bit more controllable. Not only did the CST5 Mazdaspeed turbo spool a bit sooner, but we were able to better control the spool up boost curve so we could create a torque curve that was more friendly to the FWD traction. This makes the car more fun to drive. Looking at the higher RPM range we were also able to hold boost more consistently to 7500rpm.
We hope you guys and gals are as excited for the EWG options for the CST4, CST5 and CST6. They really are an awesome setup for any driving style and power goal.
Thanks for tuning in with CorkSport Performance.
-Barett @ CorkSport
Testing – CorkSport External Wastegate Housing for Mazdaspeed October 20th, 2022CorkSport
We are happy to release the new “medium big” brother to the tried and true CST4, the new CorkSport CST5 Turbocharger for the DISI MZR engine found in the Mazdaspeed 3, Mazdaspeed 6, and Mazda CX-7 Turbo. Finding a middle ground between response and top end power is always difficult when selecting a turbo, yet we believe we have nailed it with the CST5. You get the response of a smaller turbocharger yet retain high horsepower capabilities of a big turbo.
CST5 Mazdaspeed Turbo
Before we get into power, let’s first discuss what makes the CST5 tick. It’s all started with a proven MHI journal bearing center section. These offer great cooling capabilities and fantastic reliability, especially when combined with our high performance journal bearings and 360° high performance thrust bearing. The CST5 can seriously take a beating, and does it in a package that fits perfect in the OEM location.
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CST5 Billet Compressor
Attached to this center section is a compressor and turbine wheel combo that is a little unconventional. Creating boost is a tried and true GTX71 billet compressor wheel that is rated at 56lb/min. The turbine that drives the CST5 is where things get a little interesting. Instead of a standard GT30 10 blade wheel, we chose a MHI TF06 9 blade design. This offers a number of benefits that make the CST5 outshine a comparable 3071 setup. One less blade means lighter weight for faster spool times and higher maximum flow capacity. The TF06 design is also slightly larger than a GT30, yielding a better wheel size ratio for more efficient turbocharger and engine function. For full info on the wheels and what they mean for your Mazdaspeed, check out our design blog HERE.
CST5 Mazdaspeed Turbine
The new wheels are wrapped in new housings. On the compressor side, there is a 4” inlet that includes anti-surge ports for optimum compressor operation and longevity. This large size also maximizes efficiency for 3.5” and 4” intakes. The turbine side is where there are the most differences from the CST4. The A/R has been increased from 0.66 to 0.82 which provides more top end power to match the rest of its big turbo characteristics.
CST5 Internal Wastegate
Now, what does all of this tech mean for you and your car? If you have a stock block you can easily max out power (~400WHP) and stay safe on your rods. Due to the bigger size, the CST5 peak torque is slightly later than the CST4, keeping you safer even before tuning is considered. Having a built block is where things really get interesting. The CST5 will make~450WHP all day on a “calm” boost level of 25-26psi. If you really want to push it though, the CST5 has made ~520WHP on ~30-31psi. This versatility allows the turbo to grow with your build. So even if you are stock block now, the CST5 can carry you even after you build your block.
The wheel and housing options delivers great response as well as great power. When pushed to its limits on a built block, 20psi was hit at 3400-3500RPM with 30psi hitting by a surprising 3700-3800RPM. Obviously this isn’t stable for a stock block but is possible on fully built cars with full bolt-ons and a high flowing head.
CST5 Internal Wastegate vs. External Wastegate
The versatility continues as the CST5 is offered with internal wastegate or external wastegate turbine housing options. The internal wastegate setup is the best if you want an easy drop-in fitment with great boost control. The external wastegate setup if you’re willing to take a little bit more time for fitment and spend a little bit more money on the external wastegate itself for the best in boost control. The EWG setup offers some great new sounds from a screamer pipe as well. As for power, they are very comparable, as shown in the graph above. The EWG setup makes just a tiny bit more up at the peak, but that is likely due to small variances in tuning. While only the IWG setup is offered at the time of writing, the EWG is coming very soon! Lastly, if you must have a CST5 now, don’t worry, the EWG housing will be sold separately if you want to upgrade down the road.
Both the IWG and EWG options come with a full hardware kit that includes everything you need for install. This means all coolant/oil lines, new gaskets, new crush washers, and even new studs and crimp nuts for both the turbine and downpipe flanges. The EWG setup includes a custom designed elbow for great EWG actuator fitment on Mazdaspeed 3 and Mazdaspeed 6, and the correct clamp to attach it to the housing. More info to come later on an add-on screamer pipe option.
CST5 Turbo Hardware Kit – Included!
Each CST5 Mazdaspeed Turbo also comes with full CorkSport support, including full-color install instructions, a 1-year warranty, and assistance with any questions you may have. We are extremely excited for you all to get your hands on the CST5 and start making even more power so please check out the product listing for full details and to place to order.
