I was actually hoping to build a 500ish hp engine, it was suggested that I rebuild the lower because of how high I wanted to go. If I am going to leave the lower stock, how much of it do you suggest I leave stock? I'm buying a n/a and looking to put a xpz cam in it first off. Should I get that professionally installed? I've yet to do anything like this but I really want to try, any help is greatly appreciated! Support is always helpful.