[thstone]

Originally Posted by Greg Holmberg

So, remind me--you currently have semi-solid mounts on both the engine and trans, right?

Correct, both engine and transmission are semi-solid mounts.

Originally Posted by Greg Holmberg

So you've concluded it there's no downside to them (no loss of engine power), but did you find a benefit? Better throttle response? Better handling?

No loss of power that I could discern in wheel to wheel racing. The increase in NVH was substantial and readily noticeable but not so uncomfortable that this would cause me to switch back to the OEM mounts based on increased NVH alone. Please note that this is for a race car this is only driven to/from the track. I'd never want this in a street car.

I did not notice any benefit either. The car felt the same in terms of handling/throttle response and my lap times were consistent with the lap times that I posted in April at this same track (within the range of my ability to achieve consistent lap times, differences in tire wear, track temps, air temps, phase of moon, etc).

Originally Posted by Greg Holmberg

Would you recommend using semi-solid mounts or not? What are your reasons?

At this point, I'd have to say that it may not matter for someone at my level of driving skill since I couldn't notice a difference. Theoretically, the semi-solid mounts should help handling but maybe its differences of one-tenth here and two-tenths there while I am still chasing 1.0+ second differences.

I plan to keep the semi-solid mounts in for my next planned race with PCA at Willow Springs in two weeks so I'll have another data point from that race.

But after that race I am going back to the OEM engine mount while leaving in the semi-solid transmission mounts with the goal of eliminating ANY chance of loss of power yet get whatever benefit in handling that might be gained from the semi-solid transmission mounts. This is the more traditional Spec Boxster configuration.