i have a 94 325 IS and when i am doing 80 mph my rpms are about 4,250 give or take 50... this just seems like lot to me, so i dont know if someone changed the rear end out of a four banger (if the gear ratio is different) but i dont know?.. My car is a five speed. My mustang is a five speed as well with a v8 pushing 450hp with 3.55 gears and it doesn't even spin that fast at 80mph. so i am just wanting to know if what the I6 five speed gear ratio is to an I4 gear ratio??