The other reason for the turbocharger choice was that due to probably a large proportion of the vehicles being fitted with a CVT, we did not want a laggy turbo that all of a sudden increases torque and power over 1000rpm like some and then puts major pressure on the CVT. We opted for a billet turbocharger that was going to max out at about 400hp at the engine with standard compression so that it was responsive down low and also could rev to redline. This would mean designing the manifold slightly unequal 4 into 1, it was not easy to do within the confines of space that was available but it was achieved and with the standard position exhaust system still being able to be fitted. While designing the kit, another aim was to make the boxer sound more prominent compared to its non-existence in standard trim. So we thought to do this properly that a whole turbo kit which included manifold, turbocharger, oil and water plumbing, inlet hose from airbox to turbocharger entry and intercooler hose from turbocharger compressor outlet to hot side intercooler entry would be necessary. The detonation issues then led to engine failure. Once boost was increased even with an upgraded exhaust system, the back pressure caused by the small manifold runners and small turbocharger increased to a point where it caused cylinder pressures and then detonation issues. After much testing with the WRX 2015+ vehicles concluded that the standard turbo and manifold setup was a major restriction when wanting to increase your horsepower and torque.

2015 wrx upgrade turbo