Before i got my Dart with the auto trans ,i raced a 4 spd car.Granted it was a low 13 second street car ,but i powershifted religiously and broke stuff constantly (clutches ,axles ,bearing straps in the rearend).I think its easier to just stick it on the floor than to let off and stick it again while shifting .I fine tuned everything for perfect operation( clutch linkage ,pedal hinge,shifter linkage ,etc.) and installed a rubber bump stop like was mentioned earlier under the clutch pedal on the floor ,and had only enough play to disengage the clutch enough to shift.Lots of fun ,but can be bad if you have weak components in the driveline.I never broke anything off the line ,it was always when i grabbed 2nd gear .As far as the ET's went it picked up a half a second or so powershifting and sure sounds cool...