what rumrumm posted is right on the money . i will add is the ls1-6 is a very good engine and can take alot with not to much done to them . any 7000 rpm engine on the street will kill valve springs .you will have to stay on top of it checking them all the time all valve train has to be top notch as well as the bottom end. build the engine for low rpm TQ you will be much more happy