Installed the UUC (Competition) just before heading up S.C. for the "Experience". Was very easy to get used to. Little bit stiffer on the 1-2 shift, but, the rest are definitely quicker and more precise in their feel.
I think Hennessey buys their shifter from UUC. They don't make their own shifter.
Speaking of shifter experience, I had a UUC competition shifter in my '98 540. The throw was very short but it was also very hard to shift. I later switched to their Evo shifter and that was much easier to shift. The throw is not as short but is still shorter than stock.
The 1-2 throw is still better than stock to me. I tend to really hit it hard any way, so the extra effort lets me know I've made the change. I'm still working on my starts. While I can get off the line quickly in first, I still tend to spin the tires on the 1-2 change. Instructors said I was moving too fast and needed to slow down my shifts.
Some thing about "Premature Engagement" ?
I installed the UUC Motorwerks Competition EVO w/ERK in my M5 at 4300 miles. I've now got about 11,200 miles on the car. It will add a little notchiness compared to the stock shifter. Not objectionable, but discernable.
As far as I know, UUC supplies the shifters Hennessey sells.
I received my M5 in October 99 and installed a UUC short shift kit in Feb 2000. I've now accumulated approximately 7000 km with the short shift kit. I purchased it from John Hennessey and do not believe it has the effort reduction option (ERK). I prefer it to the stock shifter but it still compares unfavorably to a world class shifter like the stock shifter in my NSX. I find it impossible to comprehend that BMW intended the M5 shifter to feel like it does but they can make a shifter I like (e.g. the M version of Z3).
To be more specific about the UUC short shift, downshifts from 2-1 feel "rubbery" and require a deliberate and forceful shove. The gates are better defined than with the stock shifter but you do not feel them as you would in a sports car. I havn't missed a downshift from 5-4 but can see how it would be possible to accidentally downshift from 5-2 potentially causing serious engine damage as has been previously reported on this messageboard. This might be especially risky for a neophyte to manual shifting or a devotee to BMW shifters. I can not describe the UUC shifter as precise and it certainly does not feel notchy to me. Shift throw is however shorter. Overall, shifting effort is significantly increased. My wife, who is 110 lbs but strong and athletic, finds the shift effort excessive and actually uses two hands to engage reverse. She finds the gates v a g u e and does not have confidence that she has engaged the gear she wants but also hasn't missed a shift yet to my knowlege. UUC's web site provides shifting instruction which seems quite good to me - their technique is very similar to that which I was taught when I first learned competetive driving and which I use successfully in my M5. It is however very different from that taught by our local BMW club for use with stock 3 and 5 series shifters - I've tried that method with my UUC mod and it definitely does not work well! You may need to change your shifting technique to use the UUC shifter. From other's description of the UUC mod on this messageboard, it seems that individual perceptions and expectations of a shifter vary enormously. In a perfect world you would try someone else's before modifying your own car.
I tried to contact AC Schnitzer about their short shifter but never did receive any information. I spoke personally to the sales manager in LA twice but he did not call back with information as promised. My local BMW dealership has had similar experiences so it appears that UUC is the only realistic alternative to the stock equipment today.