Mugen on-road clutch is the one most people use. Also Mugen 2-speed trannys. No problem with the speed of the shift I don't know where that came from. Once the finger or shoe is moving fast enough it changes gears. The first gear is on a one-way bearing so once the 2nd speed engages the first gear is just along for the ride. Single speeds are faster but not many of them in anything but rail type cars to date. A few direct drives in the door cars but not many. Hard to find the finger type mugen tranny's now. RS4 finger is what people are using. I prefer the shoe type with lightened housings myself. Harder to learn to adjust but unless you go to the trouble of getting somone to make a 3 peg housing for the 2nd gear the finger type can take up to 1 full turn to engage or more if its worn. Adjusting the clutch is critical if you go for a single speed. Not something you'd want to tackle if this is your first car. Look for a light alloy clutch bell and pressure plate when you are buiding up the clutch. Also light alloy parts for the tranny cluster. The lower the weight of any rotating part the faster it will get up to speed.

Griz