Those superchargers work well, lots of off the line grunt. I put together a 347 for a friend of mine, it had iron world products heads, a weak isky cam (he picked it out) 750 carb, etc... just under 400 rwhp, like 397 or something with the pulley that comes with the unit ( I think it was 5lbs). He proceeded to go with 14psi boost, and blew the head gaskets. He was able to successfully run 14, but that supercharger made so much heat it had to be tuned real conservatively with timing and fuel to keep it from detonating. He's going back to 5psi, and building his 2nd c6 for this thing.