Yes, I am probably the one credited for coming up with the idea and implementation. If you are going to have the trans worked on then it's a viable option. Otherwise its pretty expensive to have done for just that since there is a lot of labor to R&R the trans.
Cost runs about $300 for the gears and mating work in addition to the regular undercut service ($350 and up).
expect 20-25% RPM reduction in fifth gear. 80mph is only 4000rpm.
The factory trans is already undercut but this allows for better enguagement and is good for both street and race.
Sean Morley