Am I correct in thinking that i can change the exhaust system on my car ( full exhaust inc down and up pipe) without worrying about boost levels? The car is a 2002 wrx ppp?? Standard otherwise.

 

im quite sure you will need a re-map
if it was a backbox you would be ok

 

I am pretty sure you will need a remap as your car is a newage & has 3 cats,but on a classic,if you change the middle & backbox sections they tend to be ok ,however some people who have changed the cat for a decat have had boost issues with the ppp fitted.