I have a 2009 silverado 4.8L v8 I have recently installed an AFE pro dry intake system and a diablo predator programer. I was told that exhaust kits would be pointless and to only get the magna flow muffler and possibly headers. Any thoughts?

 

longtubes and some kind of free-flowin exhaust will open it up a lot..that programmer ain't doin much for you, I promise. get a tune when it's all said and done. Wheatley or blackbear will do the trick