Originally Posted by Keiichi
so you'd rather buy a cat-back later instead of now? if you're going to upgrade your headers and x-pipe, you'll want to upgrade everything after that as well. might as well get a cat-back now. i'm not sure about the 4.6's, but installing a cat-back (going from 2.75" to 3" tubes) does add power even through stock manifolds on an LSJuan.
I'm sure it adds power, but your talking a pretty small amount. I'm leaning towards not buying a cat back, just the LTs, and x-pipe and then just using a high flow muffler in the end. Thats my goal, but thats a lot of money and time down the road yet.