Have you had your car recalibrated for the 3:73 gears? Something you have to have done for Ford or an automotive shop. That might have it thrown off.I have a 2013 mustang premium and my acceleration timer I feel is wrong. it's saying I'm 0-60 in 5.6 sec when I have cai bama hybrid tune ported throttle body and 3.73 gears. how accurate are these things? I have done a few pulls with a few respectable cars (at the track) and won.