Tuning tips for the Subaru Impreza WRX and STi

"That does Impreza me much!"

With their phenomenal success in rally, Subaru have really carved out a nice and created a truly easy to own high performance car.

The WRX an STi both appeal to those with family obligations as they are such good all round cars. The engines are very solid and can tolerate a great deal of tuning.

There was a problem with the early fuel pickups which would cause fuel starvation on long fast sweeping bends. A new design pickup/pump will address this issue.

The flat four boxer engine is certainly one of the most distinctive sounding engines around, and the engine configuration means that the weight is carried low down in the engine bay which helps the handling characteristics.

TorqueCars would recommend the following tuning modifications for the Subaru Impreza WRX and STi. Firstly the turbo can fairly easily be upgraded with one which has re-machined internals. A remap will yield large power gains but this is best left until last so you can wring out the benefit of all of the other modifications you have. If you increase the power you will certainly benefit from an uprated intercooler, indeed many owners of standard impreza WRX and STi report a power increase from adding an intercooler.

A sports cam profile will lift the power in the upper part of the rev band, however this will affect the smooth tickover of the engine so this is only really recommend for serious track day use.

If you fit a lighter flywheel your engine will be more free revving and will feel more powerful. You will also certainly want to uprate the clutch although the original clutch should be good for 350 bhp, unless it is particularly worn.

The engine capacity can be increased to around 2.5 litres. This should not overly affect the reliability of the engine but we would recommend a thorough testing of your block for fatigue. A sports catalyst and sports exhaust will help the breathing of the engine.

If you are increasing the power by a significant margin you should also uprate the fuel pump and injectors to keep the air to fuel mixture within their optimum parameters.

Read our tuning articles for more details on the many Impreza modifications available. It would certainly be worth you joining our friendly Impreza owners forum where we debate all types of modification and tuning for the full range of Subaru engines.

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