I personally think its more accurate the way it is now. I have adjusted my speedo with the xcal and everytime I passed one of those speed signs they clocked me 10% slower than I was going. When I set my speedo to stock with 32s the speed signs have always been fairly accurate.
To answer your question though, I have noticed about a 10% change in the speedomoter readings (basing it RPMs).
Last edited by TommyC; 12-21-2007 at 01:00 AM.