I just put a 3" cat-back exhaust and a 3" downpipe on my 97' gs-t. Now i am loosing backpressure and can't go past 5,000 rpms. what size headers should i get to fix this problem?? im also putting my front mount intercooler in at the same time?? any chance the front mount will fix the problem w/o me getting headers??

what do you mean you can't go past 5000 rpms? if you just mean you arent making any power up there its because you have a stock turbo. 3" exhaust isnt nesessary for a stock turbo but it helps a little and you certanly don't have to worry about any lack of backpressure with a gst.

back pressure on a turbo car? all bets are off with a turbo car no need for backpressure. you can run these stright off the o2 housing if you want. even a stock turbo will put power past 5000 rpm you have something else wrong with the car.

yeah you guys were right my IAT sensor was bad, cars allset!!