Hey man, I have the exhaust you need. Full three inch custom setup for a p5. Pm me your email or cell and I Can send pics. I ran this setup with a pope downpipe
some people run a stock protg ecu and a piggy back of some sort with a o2 voltage clamp. The car therefore will run of the stock ecu until once you start making boost, then it switches to the maps on the piggyback