i think you may be right about compression,we don't know we bought it running,it has a 4.30 gear,727 trans,10" converter.we use an msd with 2-step hooked to the brake light switch & leave at 3000,it runs 8.30 in the 1/8th at 83 mph,60 ft is 1.80--hate to disassemble it to find out whats in it & compression ratio,it runs too good