Yea, the stock mufflers are way two heavy. Get rid of them and your vehicle will go faster and use less fuel, IF you do it right. I am pretty good with TIG welding stainless steel. I'm using a Corvette X pipe, then some Vibrants in parallel, followed by two Magnaflows in parallel, with some black 4" Chevy truck tips. Sound is pure evil, but not "loose your hearing," loud. That NorthStar V8 is a business machine and I want other drivers to know I'm not driving a toy; love scaring the **** out of the Prius driver who don't belong in the left lane on the freeway.
Flow Master and Dynaflow say they make mufflers, but they are all only resonators, SO always have two in a series, four total in parallel for the XLR. And you can fit resonators aft of the X-pipe in the tunnel despite what some muffler installers say; just weld on some braces or your going to get metal knock (it's a tight fit).
Has anyone changed out mufflers for Borla? Want a little more growl out of my 05. Also my set up is 2 3/4" in and 2" out. Can I change to 2 3/4" all the way to the tips? If you have changed mufflers and have a better option, please let me know.