No, indeed that would be odd. You can only really run very heavy diffs on smooth tracks, and I understand yours is bumpy, so that's why you have softer diffs. Yor setup does sound light to me though, for any track, still you've been running buggies longer than I, and I bow to your wisdom. I'm currently running 5-7-1 in the XB8, but as I have mentioned, my track is bumpy and technical, so I have to trade off a little my driving style in favour of keeping some forward motion.