My combination was on a 3100 lb swinger 4 speed 340 car I ran gear ratios from 355 to 430. I ran both an ld340 and a stealth manifolds prior to my m1. my car was 100% Street and the m1 was just Superior really didn't care about under 3000 RPM performance ,with the thermaquad combination it never seemed to be an issue. Throttle response on the m1 was beautiful in a whiplash kind of way!