I just test rode my 11' 300 EC Six Days after Dave at STM suspension re-worked my forks and shock.
http://www.stmsuspension.com/
I previously had the forks re-valved but didn't notice much improvement in the ride quality, so I called STM because they re-valve the shock and forks and I believe that both ends of the bike need a lot of help when ridden stock. I ride in Northern California and we often have dry, hard clay-filled dirt with lots of sharp bumps and rocks. We rarely have soft or loamy dirt and the conditions can be so dry that the rubber from tires is visible on the baked dirt (we call this "blue groove"). I'm a 50 y.o. 'B' rider and I occasionally race cross country (hare scrambles), so a good suspension is essential for me because I have limited energy and endurance compared to younger guys.
Today I test rode the bike with STM suspension mods at Hollister Hills OHV in some nasty rough, dry, and rocky conditions. The difference from stock was a noticeable dramatic improvement! For the first time since I bought the bike last March it finally felt good in these demanding conditions. The harshness on both ends is gone and the bike requires much less effort to control. I can even get lazy and sit down while going fast, something I could never do with the stock suspension. The rear shock was previously not able to follow small sharp whoops and I had trouble maintaining traction. With the STM mods the rear end is well behaved and predictable. Most importantly, my lower back isn't in pain after 2.5 hours of riding! The forks also feel great, much less harsh than before and the feel in corners is greatly improved.
I highly recommend STM suspension mods for Gas Gas. These guys understand how to make the bike work properly in demanding conditions and your money will not be wasted. My modifications cost approximately $750 and included new springs (front and back) re-valve both ends, servicing of all components, and return shipping. This is a reasonable price for this type of work, especially when the results are this good!
Steve