Pro's/Con's to this setup???
 

99 WS6 - I have an SLP Loudmouth II catback, K&N, and a whisper lid done to this car and that's about it. The next couple of things I want to do is a FAST LSX intake & 78 mm TB, Granatelli 78 mm MAF, and SLP Offroad Y-pipe. What I'm curious about is if I were to go with 90mm induction instead of 78mm would I also need a set of LT headers or could I get away with just adding the Y-pipe? What do I stand to gain/lose?

i put on the fast 90 90 when i still had stock manifolds, fealt a difference, but when i put lts on it realy woke the car up