DP, exhaust, AP, and a good tune are a good place to start. I was told that the stock turbo can't handle the amount of air form a CAI thus producing less power. I have a K&N typhoon. i put it on before the car was modified and lost low end power for some sound. it quickly came of and is sitting in my garage in a box.....do you want it.

 

CAI is fine as long as you have a tune that accounts for it. I don't think the APS intake can be beat as far as performance is concerned.