Woodsman, mine are 73 bottom( I think, I can't see the # at the moment, LOL) and 56 top. I don't care if I run a little more boost so long as I can keep it under the hood. That set up was suppose to be around 18 PSI but I don't know how to figure it. I may have to look into those bowls as I have the factory style on my C&S blow through. I'm also running their regulator on my set up. Right now it being cold and my car not in the garage my big hang up is mounting the intercooler.