What mid pipe are running..... Stock or O/R ?
Try the SLP power flo or pypes mid muffler ...if you have the cash CORSA all the way !
If you have too many ? check out the muffler mid pipe combo thread in the TECH sticky area ! Answered all my ? for what I was looking for !
PYPES MD then , my buddy had them and even with an O/R h pipe there great Highway speeds !