Not sure which 2003 GMC Sierra Exhaust, Mufflers & Tips are right for you? We have over 4515 customer reviews, with an average rating of 4.5, to help you find exactly what you're looking for. Here's what some of our customers have said:
"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." —Matthew M from Durango, CO bought a Gibson Exhaust Performance Header for a 2003 GMC Sierra.
"I ordered the system and got it on the expected ship date. The bad news...I don't know if it is like this for all the models but on my 03' 8.1 Sierra Shortbed it didn't fit right. The dual inlets don't have the right bend to them and I had to bring it to a muffler shop and they fixed it up for 70 bucks. Other than that...ITS AWESOME. It looks really good and you can definitly hear a difference. I had about a two mpg increase which helps with that gnarly 496. It definitly had a performance increase. I am not sure about how much but it was substantial. Overall a good package." —Matthew M from Durango, CO bought a Flowmaster Exhaust Systems for a 2003 GMC Sierra.