TMK Heidt's, like Fatman, only has a good rep with hotrodders. Not real performance guys (open track, etc).
HTH has the truck arm setups that some people really like.
Lateral Dynamics makes a 3 link setup the track guys love. I think the exclusive dealer is ATS (
http://www.t56kit.com/) - a guy named Tyler runs the place.
Then there is Air Ride Tech (
http://www.ridetech.com/) - they use the chris alston g-bar as the basis for their rear setup. They flog the crap out of their stuff at autocrosses and such. The air spring concept is neat if not expensive. You can theoretically dial in each corner spring rate, but I’m not sold as I fear the effects of total spring failure (like the guy who won the burnout contest at Carlisle). They might be at good guys in PA at the end of the month, might be worth your trip there (or Rhinebeck in week or 2).
Art Morrison is another place to look. And maybe speedtech. Martz makes a front subframe, but most everyone appears to believe it is a flimsy POS.