[Sempai]

...not legal for street use.

This is an issue you might want to check with your local DOT. Fact of that matter is that most all of the handicap equipped automotive controlling devices are not legal for use...'by other than the intended handicapped driver.' Generally speaking, this wouldn't be much of an issue if you haven't any use of the throttle wrist, but to be safe, you might check with your DOT.