Tested on my '95 SC
ROAD
My car is already setup pretty stiff. H&R Springs, Koni Shocks (set + 1 1/2 turns from full soft), Delrin IRS Bushings, 1 3/8" bars F&R.
Even so, I was expecting a fairly dramatic change, and a noticeable increase in NVH. However, the change wasn't all that much. There is a slight increase in harshness over expansion joints and the like, and a little more mechanical noise, but not much. I would have no issue using these mounts on a daily driver.
I made the round trip to Englishtown (70 mile round trip) today on DR's, so I didn't push too hard in the corners, but it did feel more stable. I'll take a road trip later this week on my street tires, and push a little harder.
TRACK
On 3/10/2010 @ Englishtown, I had my best previous results. The DA that night was -912 feet.
My best ever 60' was 1.765
My best ever ET was 12.925
Today I went to Englishtown again. The DA today ranged from -685 to -558 feet.
I made no changes to my car, other than the UHMW sub-frame mounts.
Same tune, gas (Exxon 93), tires (MT 275/40-17 DR's), tire pressure (20 lbs.), and the same launch RPM (3,500).
My new best 60' is 1.742, and another 1.759
My new best ET is 12.879, two others were 12.921 and 12.913
So, in worse conditions, I picked up .023 on the 60' and bettered my previous 1/4 mile time by .046.
Most noticeable was the lack of drama during shifts. Previously, the car sort of shimmied when I shifted, today I felt none of that.
I'm quite pleased with the early results. I think with more passes I can improve even more, now that the car is planted better.