Blower size and amount of boost
To clear up my question. I was looking at a 4-71 which would produce a max of around 22 psi. and I was told I should go with a 6-71. that it had a standard pattern for an injector setup.
the 4-71 would make around 18 psi @ 20% over, and a 6-71 would make 18 psi @ 20% under.