VW Golf 7 GTI 2.0TSI - Stage3 Boss500 GTX28 98RON - Etuners remap

There is a very fast white Golf Mk7 GTI in the streets of Oman, running on an upgraded turbo setup. What initially came as a very problematic Boss500 CTSturbo kit that did not work, was transformed into a beast of a turbo. Based on a Garrett GTX28 core, this turbo is quick to spool and produces very good power at high boost- exceeding the usual IS38 levels by far.
The problem with the kit, as with most of the boss series, was that the wastegate design was very problematic. The port itself did not seal properly because it was badly machined and would not shut completely, leaving the car with no good boost at high rpm. We spent days on the dyno trying to find out what the problem was and several emails between the turbo kit’s manufacturer going back and forth.

Boss500 CTS turbo kit - problems with the wastegate port

In the end, the turbo kit came out of the car, the internal wastegate port was welded shut and an external wastegate was installed onto the turbo housing. The problem then was, what to do with the electronic wastegate that Gen3/MQB EA888 utilises for turbo control. A very special hack was done in the ECU software that allows us to bypass EWG control and use pneumatic wastegates and a boost controller. So that the owner can set the boost level at whatever he prefers. With this setup, the turbo kit works flawlessly and holds boost as it should, at high rpm.

Upgrade specifications

  • 98RON
  • Modified CTS Boss500 GTX28 kit
  • Upgraded exhaust
  • Upgraded intercooler
  • Upgraded cold air intake kit
  • custom #Etuners Stage3 ECU remap


Performance results

  • Maximum horsepower at the wheel: 440whp
  • Maximum wheel torque: 437.79 ft*lbs

VW Golf 7 GTI 2.0TSI - Stage3 Boss500 GTX28 98RON - Etuners remap

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1 Comment

  • Rob Higgins Posted October 23, 2020 5:08 am

    I am very interested in this external waste gate idea curious on how it was done and if i could see some pics of it.

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