08 silverado upgrades

I have a 08 5.3 silverado crew cab. I have currently made the following upgrades K & N air intake system, Flowmaster Super 40 Exhaust and a Diablo Predator Programmer. I have not put the truck on a dyno, but I've been told it should be around 380 hp. Is this info correct. I am looking to make other upgrades and try to get around 650-700 hp. What do you recommend as my next upgrade(s), Turbo, nitrous?? Please help I do not know a great deal about truck performance but a huge addict on the issue. 
 
Thanks,
 
Heath

Welcome to the forum!!! Someone here should be able to give you some ideas, just hang in there.

I just purchased a 5.3 silverado also, im pretty sure the intake/exhaust will just help you get more of the 315hp out of the engine and not actually get you more then that. the diablo should get you to around 330hp im guessing.