I'm building a S4 6 port motor with S4 turbo rotors, with large street port irons & exhaust ports. This motor will be paired with a roots type blower running 18 psi. I'm trying to decide between a weber 48 & a 50 doc carburetor. I understand tuning will be very important, but I need to start with the right carb size. Once this set-up is running well, I plan on turning up the boost. Can anyone give me insight on which carb is best, and maybe a suggestion on a baseline tune?