I put some H&R coilovers on my 02' 996TT a while back, they've since failed. I installed a speaker box which made the car a little heavier in the back. I chose the H&R's because having the adjustability to keep the car looking even was important but was probably a factor in them failing.
Put in a call to H&R and they do not re-build them. Also called Bilstein and they could do a re-build but the turnaround time was a couple of months.
I'm debating to either get new shocks and lowering springs or going with some low end coilovers like the D2's, BC Racing or KSports. I only