We installed the Pure Performance long travel kit that replaces the torsion bars with a dual coil over setup on my 2500HD and I really like it, but have not beat on it in the desert yet... We have a lot more work to do on the truck to finish it up first. We also beefed up the steering with their linkage included with the kit my truck does not toe in under power on boosted 4WD launches in Dirt Drag racing or sled pulling like nearly every other IFS Duramax truck I've seen... BUT, I think they discontinued the particular kit that I used and are now focusing on the newer generation trucks...
www.pure-performance.biz is their website for you to check them out. I believe they spec the suspension at 14-inches of travel, but it seems to stiff and heavily sprung to measure it out with out pulling the shocks and cycling it and I haven't had the time to do that yet...
We also beefed up the IFS front diff and the article for everything we did to step up the IFS is in the current issue of Ultimate Diesel Builder's Guide magazine that is on the newsstand right now. We installed an ARB locker and G2 gears along with Fleece Performance TuffShafts in the center section including deleting the center axle disconnect. Then for the CV shafts we replaced the stock CVs I was using with Branik motorsports 300M billet extended length axles with a set of RCV Ultimate axles using the 934s inboard with adapter plates and their spherical outer. We have had no problems so far and this seems about a bullet proof as you can make the factory component up front.
I am looking into reworking some of the front end to get some more travel and longer shocks with a singel coil over and a bypass, and hope to desert race the truck when we are finally finished with it. Most of the build up on the old pig was covered in articles in Diesel World magazine.
I hope this helps...