I have a 2007 400EX with 450r front shocks. I recently had all three shocks rebuilt, re-valved and re-sprung by Bart at Shockworx in Trenton, MO. I also had him install a GT Thunder rear link. I took my entire ATV to him, so I knew the job would be done right.
I am incredibly impressed with the results. I am not a racer, I am a recreational rider who wanted a plush ride. Bart provided that plush ride!
The front shocks are now dual-rate and soak up nearly every bump I come across, but also provide amazing cushioning on the minor jumps I attempt. The rear shock and link are even more amazing in the difference from stock. The rear end has absolutely no bucking anymore, and it stays planted no matter what I am riding over. The rear also soaks up my minor jumps with no problem, and no bottoming!
I highly recommend Bart and Shockworx for your next, or first, shock rebuild. His prices are right, and his customer service is awesome.