When you're setting up a part, it's just as easy to do it 2 deg as 0 deg, but not so easy to mount a new perch at 2 deg for a 'hot rodder', and in hot rodding I really doubt the 1/8" to 1/6" deviation of the perch as the spring goes thru it would matter (much). Maybe the rubber cushion will 'wear out faster'?? When I cleaned up my rear end/springs/etc, I used the original cushion as it was good!