Originally Posted by c0ckac0la

2005 Ford F-150 4.6l 2wd dyno test with JBA cat4ward headers and JBA Catback split dual exit exhaust system.

Considering the stock exhaust is pretty efficient in the 04 & 05's, the increased gains are mainly from the headers. However, as it would be a big waste to free up all that exhaust pressure at the engine end and than bottle neck through the stock exhaust, I dropped the $$$ and got a more "flow-thru" system. Truly my only regret is not having added an intake system yet....but that is in the works.

If you want more info or pictures of the install check my gallery for the magazine shoot, or read the thread I started back when I had them installed:
JBA headers & SIDO Install w' StreetTrucks Magazine Article (long)

My Truck is in a Magazine!!!!

There are some video/sound clips on the second link. They're about a year old, so the exhaust has a deeper and slightly louder note now then when compared to right after install.