Dougie i would be curious to see some dyno slips at different psi. Our engine requires 172 CFM N/A at 72% efficiency, 230 CFM at 100% efficiency and the max the 42 A/R will flow is 360 CFM. Thats only 188 CFM for growth while Induction is forced. Now i am not saying our motors will operate at 100% efficency but if gives you a curve for improved efficiency when boost comes into play.

My point is i doubt 14-18 PSI range makes any difference other than spool time and additional heat is introduced.