Originally Posted by ZAHANMA
Someone can correct me if I'm wrong, but the main gist of the losing torque in the lowend with exhaust modifications (unless you go all the way up and start at the headers) is related to the loss of backpressure.
If you start at the headers and make your changes starting there, that is a different story. The extra pipe and close to symmetrical length in aftermarket headers would help...but there just isn't anything on the market. Those would have to be one off headers.
There are only a couple of guys here that have that done, the only one I can think of currently is Colin (trizombie)...but I know there are a couple others.
I got the old LET shorty headers on mine and I recently got a new exhaust (cat delete/res delete/ real dual exhaust/dual magnaflows). Seat of pants view is that it gained some rwhp. I dynoed it before without the headers and with stock exhaust, mail in tune, and single Needswings CAI. It was 347 rwhp. Feels alot stronger now.