I have the SDR Motorsports kit and I love it. Its really good in the rough stuff. Very well built too, nice and strong due to the boxed design. Tim at SDR will be selling the exact same kit that Mason sold, built by the same manufacturers. So Im sure the quality will stay the same or get even better. Also, Tim is known for his great customer service, so thats always worth alot in my eyes.
We run the LT6 on our race rhino with the stock shock mount locations (for the time being), with the FOX external resevoir comp. adjustable shocks. My buddy also has the same kit on his 4 seat desert cruiser, but with the FOX piggybacks.
We are both very happy with the kits. If you have any more specific questions, let me know. I havent had a single problem with mine.
Also, I upgraded my kit by replacing the upper control arm adapter bolt with a 5/8" bolt and uniball missalignment spacers. (had to drill out the spindle). Mason supplied all the hardware for free for me, after I contacted them about getting a new adapter bolt that I had cross threaded. Much beefier setup. They suggest it for racing, and I can see why.