Reviewed By Matthew M (Durango, CO) Reviewed for a 2003 GMC Sierra —10/29/2007 7:43 PM
I bought these headers for my 03' GMC Sierra with a 496 in it. I already had a flowmaster cat-back system which sounded nice but these really made it roar. They definitly boosted overal horsepower, and aided the exceleration. They were most notable in the bottom to mid range, but also give a little extra at the top. The only problem is it made my gas mileage go down about a mile, but its a 496, it has bad MPG anyway. They really are very high quality I highly recomend them.