I've a 92 NSX and had a lot of work done a Burrard Acura in Vancouver. They're a pretty good bunch there. Last year I put in an ACT clutch and Hewie, one of the service guys was trying his best to get me to put in the Japanese gears while the transmission was out of the car.
He mentioned that he drove an NSX with the shorter gears and believes it helps out acceleration better than a supercharger.
Hewie said that they have the expertise to do the mods so it's just a matter of buying the parts and letting them go at it.
Bob.
p.s. I know a lady with a supercharged NSX and she was nice enough to let me take if for a little drive. Very nice, but pretty noisy, you sure hear hear whine coming from the engine. I might do a project NSX in a year or two. For the motor I'm thinkin of the Science of Speed Stage 3. Will very likely go with the shorter gears as I'm not interested in setting land speed records, but find handling, acceleration and breaking a lot of fun.
If you want to know more, give Hewie a call at Burrard Acura's service department. If you mention Bob with the Black 92 NSX he'll likely remember talking to me about it.