usually I try and run a 89 octane which is usuall "plus". But this weekend I sprayed a quart of water (generously) into my intake manifold while the truck was running to clean all of the carbon build up off the top of my pistons, and now no ping. But im still considering installing larger valves and all of the things i posted above, I just need to know if i will be getting my moneys worth for the HP gain.