what would i need to upgrade
 

ok so i have 2008 silverado crew cab 4.8l v8 with a 7 inch lift and 33 inch tires i was wondering what if any thing i would need to upgrade to use a performance tuner like a diablo predator or edge performance and by upgrade i mean beef up the tranny/rear end only other mad i have is a flowmaster 40 series muffler any usefull feed back would be greatly appreciated.

Upgrade to 4:56 gears or 4:10s if you do a lot of highway drivin, this will put your off the line gogo back to where it was when you were stock. Tranny put in a vette servo, shift kit and aftermarket trans cooler. Get a airaid MIT intake tube and drop in filter. No diablo or edge tuner, get a real custom tune from Blackbear or Wheatley. Handhelds are junk

ill look into those upgrades thank you

And if you want add some longtube headers and y-pipe...do all the performance mods before the tune though