Well I need to chime in here a bit. My car weighs 3100# w/out me in it. Im a good 270, so we are at almost 3400#. I just went 10.29@126 at Quaker city. Ive been running this on a Muscle motors 474 kit for sometime now. Not a really hard combo either, old Ultra-Dyne .613 flat tappet cam shaft. The heads were done by Minors engine in Ohio. Ive never had them flowed or have I ever done anything since they were done. The car is dead on and runs well anywhere. Cant knock the heads at all. I know they are not Indy's or B-1's, but they seem to work. We will be at Norwalk w/a fresh motor. Curious if I will see some quicker times over Quaker. Track was ba, but the air was great. See ya, Ken Michalik