The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

piecesparts · 10-14-2013, 02:50 PM

I installed a set of Kooks headers, 'Y' pipe and then a Magnaflow muffler with dual exhausts out to the rear on my 2011 GMC, with a 5.3 and a six speed auto. Yes the sound is different in the 4 cylinder mode and it does seem to drone a little. WIth my tune, we deleted the AFM adn now I run in 8 cylinder mode all of thetime. I just drove a 2000 mile round trip and averaged 20.5 MPG while running at the highway speeds along with traffic. I cannot complain.

10-14-2013, 02:50 PM	#7
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: Dual exhaust warning I installed a set of Kooks headers, 'Y' pipe and then a Magnaflow muffler with dual exhausts out to the rear on my 2011 GMC, with a 5.3 and a six speed auto. Yes the sound is different in the 4 cylinder mode and it does seem to drone a little. WIth my tune, we deleted the AFM adn now I run in 8 cylinder mode all of thetime. I just drove a 2000 mile round trip and averaged 20.5 MPG while running at the highway speeds along with traffic. I cannot complain. __________________ Frank