Since 2015, the Mazdaspeed 3 Drop-In Turbo has been one of the best performance upgrades for the platform.

Proven by thousands of community members, the CST4 is a perfect fit for the mildly modified Speed 3 and Speed 6 using stock fueling up to budget built engines with FBO and auxiliary fueling. Replace your KO4 with the easiest and most complete performance turbo for the Mazdaspeed and have room to grow to 450whp capabilities with the CST4.

The CST4 features a MHI Journal Bearing CHRA, OEM Fit Compressor Cover, and choice between 0.66 A/R Internal Wastegate or 0.82 External Wastegate Turbine Housings.

The CST4 external wastegate turbine housing is designed for 44mm EWGs (Tial is a great option) w/included EWG elbow pipe & V-band clamp.

Includes a FREE CorkSport 3.5 bar MAP sensor for accurate boost pressure up to 37psi.

Drop In Performance:

Don’t let the size fool you; the CST4 packs a punch for such a compact and OE fitment package. From full bolt ons to fully built with auxiliary fueling, the CST4 will support power from 250-450whp while maintaining quick spool and great transient response between shifts

Stock Flange Fitment:

The CorkSport CST4 was designed with simplicity and bang for the buck power in mind. Maintaining the OEM compressor inlet size means you can use any intake on the market designed for the stock K04. Same goes for the turbine side with OEM flanges for compatibility with your OE fit downpipe and exhaust manifold.

Billet Compressor:

Utilizing a custom MHI 18G billet compressor wheel, the CST4 can efficiently support 50 lbs/min flowrate and boost pressures to 30psi. Compared to cast counterparts, modern forge milled wheels provide higher boost thresholds, improved response, and increased efficiency to get more power form a small package.

High Flow Turbine:

Paired with the compressor wheel is an MHI TD05H high flow turbine wheel. This wheel uses a 9-blade design which reduces overall rotating mass and thus improves response and spool.

High Performance CHRA:

MHI Journal bearing CHRA housings are used for both the CST4 and CST5 turbochargers for their increased cooling capacity and proven reliability.

High performance journal bearings and a 360 degree high performance thrust bearing is used.

Comparing the compressor and turbine wheels, we have a wheel size ratio of 1:21.

Billet Wastegate Actuator:

One-off billet actuator is used for the CST4 so you can operate the turbocharger in bleed mode for the OE EBS or in interrupt mode with the CorkSport EBCS for increased boost control

All Hardware Included:

The CST4 comes will all the necessary hardware for installation saves you time and money on gaskets, studs, and the specialty parts.

Choose your Boost Control:

Do you want an easy to use Internal Wastegate setup or an External Wastegate setup and screamer pipe? You decide with the CST4!

Internal Wastegate setup includes the 0.66 A/R IWG turbine housing and IWG Actuator.

External Wastegate setup includes the 0.82 A/R EWG turbine housing and V-Band Clamp & Elbow designed for 44mm EWGs. (EWG and Screamer Pipe Not Included).

Don’t worry, if you want to change your setup from IWG to EWG later you can.

Additional Features

Vehicle Fitment: 2006-2013 DISI MZR found in the Mazdaspeed 3/6 & CX-7.

Designed in America: in Vancouver, Washington, in the Pacific Northwest.

CorkSport Service & Support: 1 year limited warranty, full color installation instructions, all necessary components, and knowledgeable telephone support at (360) 260-2675.

Advisory

Upgraded HPFP Internals and COBB AP/Tune is required with this product.

Auxiliary fueling required for peak power operation of this turbocharger.

Some aftermarket downpipes will NOT clear the EWG elbow that is included with the CorkSport EWG Turbocharger.

EWG variant designed for Tial 44mm or equivalent external wastegates (not included but available).

External wastegate is NOT included with turbo. Did we mention it is not included, because it is not.

EWG dumptube/screamer pipe is NOT included with turbo but can be added as an option.

All Corksport products are imported from the USA to the UK.