'07 Summit rear skid

usually its the springs that go first, that might be your problem. You can use thicker oil in the shocks i heard but that wont help with your rebounding, its mostly the springs that control your rebounding. You can get stiffer rear springs than the ones that come stock on the 07 x/xrs.

Two questions
Do you know what the part number is for the heavier springs?
and how often should you revalve your shocks? Rear and front for 07 X?
Thanks.

Valving controls both compression and rebound damping. Springs are for support (to get proper sag with rider weight). You can get your X/XRS rebuildable shocks revalved at several reputable shops. BJ likes Fett Bros, I've had very good luck with Hygear but am now trying Tom's air suspension in my '07 (with adjustable rebound). Most will use a higher flow piston design with custom valving to allow for "speed sensitive" damping. This means the harder the hit, the more compression and rebound damping without affecting small bump fast damping characteristics (what every rider is after). Honestly tho the '07 valving was acceptable from the factory (certainly better than all previous years); sounds to me like you lost some nitrogen charge (needs to be re-charged at least once a year).

As for how often you should re-valve... only once if you have a good tuner! You need to service your shocks every season if you want peak performance. That typically includes new oil, seals and nitrogen charge. Loss of nitrogen = loss of return leading some chasing stiffer springs and ending up with an even rougher ride.

Have FUN!

G MAN