I did the whole 520 conversion at the same time so I'm not sure if you can tell going just +1 in the rear. just doing the math in my head I'd say it would be about 1/5th the difference of going -1 front +2 rear. But then you figure in the "520 vs 532" factor and it's even less of a difference. If your gonna drop the cash for a new rear, save a little longer and do the whole conversion. But that's just my 2/100ths of a dollar.