You have to know that the 'kits' out there in the States are not the same as the Japanese made kits for other cars. These kits are made and sold in very small numbers and require lots of tuning. The Comptech is the closest to being a off the shelf system, but it is still not without problems.
I have also been told that the kits are not the best thing for the track. They can give a good burst of speed on the road for short periods of time, but with sustained high track speeds, they can have problems.
It depends on what you do with your car. If you want a high power car for the road, maybe a forced induction NSX is OK, but then I would probably go for an EVO or something else. If you want a high speed track car, leave the NSX NA, and change the suspension, brakes and reduce weight. You don't need to do much more than that.
I like the look of the Science of Speed NA tuning options. Sending the engine to the States won't be simple though. There's sure to be engine tuners here that can do the same work.
If your fear of staying alive, outweighs the thrill of making the corner, brake.