RTR tried and quickly dropped the B15. The QR produces a wicked vibration b/w 6.4K and 6.9K. After breaking motors, they tried to keep the revs over 6.9K and had no success.

Aside from RTR, the only other B15s I know of are Kojima's Nitto car (that never hit the track more than once I think) and another B15 with a NEO VVL out west in NASA. Besides those, I've never seen another B15 competing (competitively) in Road Racing or Time Attack.

If they are out there, I'd like to know!!