I have a 94 WRX with K&N 57i kit,HKS superdrager system and RCM de-cat down pipe,i just wanted to ask what BHP would i be expecting at a rolling road.

 

Depending on model (BHP you started with) you can normally add around 15bhp for the de-cat and 5bhp for the induction kit. So you should see a 20bhp ish power gain. But could be a bit less, without mapping (which will also unlock BHP)

Hope this helps .........