I'm gonna just throw in my .02. I just put on a new magnaflow muffler on my 07 4.8 and love the sound. It's not to loud and at crusing speeds to don't hear it at all. Anyways as far as shorty's go they do give you a whole lot for the 400 bucks they cost for a good set. Gibson, JBA etc. The one's for 150 from summit don't fit the newer trucks anyways. Plus they have a low heat paint on them that burns away a week later leaving rusty looking headers. Long tubes are the way to go but there's nothing really available yet for our trucks. I emailed pacesetter, who has the best prices on long tubes and they said a set are in the works. If your looking to not lose low end I'd suggest magnaflow because for the money they are a great product. If you don't mind spending more, Borla and Corsa are great as well.