I am going to have a shop to work on my engine, which has 180k km on it already (that's why a rebuild). As I will take the engine apart (the labour cost), I think it's time to give it some upgrade. I want to take the engine to around 185hp (i.e. the power of a CTR) while trying to make my car looks as stock as possible (i.e. no super huge exhaust that nearly touches the ground). What do I need to replace? Thanks.