Rep Power: 0

do the aftermarket headers bypass the cat? and how much power can be expected from getting an aftermarket header and running a test pipe all the way out to the exhaust? cuz obviously the biggest air restrictions would be the catalytic converters wouldn't it? feel free to correct me if i'm wrong[IMG]i/expressions/face-icon-small-confused.gif[/IMG][IMG]i/expressions/face-icon-small-confused.gif[/IMG][IMG]i/expressions/face-icon-small-confused.gif[/IMG]

 
Rep Power: 0

they don't bypass the cat, they are either shorty headers, connecting to the stock downpipe (cause the cat is welded to the downpipe) or they have a high flow cat built into the aftermarket downpipe. there is a lot of restriction in the cat, taking it off and running a straight pipe would be very illegal, and includes possible jail time if you're caught, if i'm not mistaken. just get the HP header, it has the high flow cat built in.

 
Rep Power: 0

Horsepower gains are modest. Most people think around 3-5HP is gained with aheader. The HP header with hi flow cat, claims a LOT more, but if you search and read about it on this forum, you will find it somewhat skeptical. There are not many hi flow cats out yet, maybe soon, Neuspeed is coming out with a header soon, and perhaps a hi flow cat. You are right though the cat is restrictive as stock. But removing it is illegal, so no recommended.