Check out this months issue of Car Craft; a junkyard Gen III 5.3 truck engine with nothing but a cam change made over 400hp. At 295hp stock, that's over 100hp with just a cam. These are awesome engines and they come right from the factory with aluminum heads and 6 bolt main caps. I bought one with 60,000 miles out of a 2002 Suburban for $550.00. There's one in this months Hot Rod (in a Ford Fairmont of all things)that has a used LS6 cam, a 70mm turbo, and no other mods making 600hp and dipping into the low 10 second range. I don't think there's a better performance bargain out there anywhere.