Paul, I just installed my third set of upper bushings by the down pipe (I have ATR headers and their 2.5 dp and my THDP both get pretty close). I seem to get about 50,000 miles before the control arm starts moving around. Two of the old bushings did not look melted or burnt, one looked a little burnt on one end. What happens to mine is that the inner hole seems to get "wallowed" out so that the bushing can slop sideways on the shaft. This lets the rear of the upper control arm move and lets the top of the spindle move forwards and backwards. You can feel a clunk when you hit a driveway slowly and if you watch from the side when someone lets the car roll a couple of feet then stomps the brakes you can see the wheel move forwards and backwards in the wheel well. Naturally this isn't good on the alignment and my tires wear on the inside tread. Anyway, I don't think any deliberate looseness would be good on a street car. As for installation, you have to unbolt the "dogbone" shaft from the frame mounts (remove the nuts, count and save the shims for reassembly, and those bolts are splined to keep them from turning in the frame) and pop the top ball joint out of the spindle, then you take the control arm over to the bench to do the bushings. I used one of those C-clamps at a friends shop to press them in and out and it was very easy. There's no way to do the job on the car, even if you pulled the downpipe (I guess maybe somehow you could not separate the arm and spindle but it's so easy why not?), so I can't think of any mods to the basic shape that would make the job easier.