i had 2 shifter karts friday nite at the dragstrip make about 8 passes each and both were hitting the traps at 94 to 97 mph in the 1/4 mile-by the sound of their motors they were running out of gear and rpm-i pretty sure they will be back with different gears and go a little faster-but from the start to about the 1/8 mile mark they were rockets,after that was when they started to run out of gear