i no every one does it but what is the performance difference
It has nothing to do with power and everything to do with the heavy aftermarket clutches people put on their underpowerd cars. If you’re so worried about crankwalk, disconnect the clutch saftey switch so you don’t need hold it down on startup. The lack of pressurized oil being supplied to the crank thrust surfaces, coupled with a heavy clutch, excessively wears out the thrust bearings….ergo you’re crank is going to go for a walk.
There is no difference in performance in mild applications however the 7 bolt was very prone to crankwalk which as it sounds is when the thrust bearings go bad and completely destroys the bottom end of the motor. This is much more pronounced when making serious power so most people just tend to swap in the older 6 bolt when they want to go fast because it is much more reliable.