while rear end is apart doing gaskets and bearings i will go ahead with the higher gears, hard to deny 15000 miles of test and tune, after 20 years of 12 mpg average anything will be an improvement, especially since it does not run on regular gas, 305 out of a 84 z28, slight mods, on reg gas it diesels, on super reg it has slight pinging, on premium it kicks butt
