for the tight budget person, (which is virtually everyone in comrade Obama's America) upgrade the air intake, the ignition, the fan, the exhaust. you already have a high flow muffler, so youll be fine. oh, and put royal purple oil in the transmission and diff. it will make the truck much happier and its proven to add horse power to the wheels by cutting friction. after the engine blows, or you know you want to drop in a replacement; then you can do things like headers, aluminum heads, and simple engine mods like porting, polishing, rocker arms, etc.