[DaveK]

I bought one but never installed it. The problems I could see were:

1. You had to cut the wiring (it could have been made a plug-in job but I guess the 50 cent connectors were just too expensive...)
2. Where the wires came out of the box was just a big hole drilled through the plastic case. No sealing or anything to protect the components inside from damp, gunk etc.
3. No way to secure it easily (no plastic 'belt loops' or anything.
4. The thing needed mounting under the car close to the vss output on the gearbox. So not really much easier than doing the gears.

The box I ordered was from Corvette Central, others may be different. I decided to get the gears from Marc.