High rpm down shifts at the road race "blew" mine out. First one side and then the other. Not intentional on my part. Sure was surprised at the increase in h.p. though, you could FEEL the difference.
Did NOT like the additional noise however. Something in between blowing them out and better flowing baffles would be nice.
Do a 4th to third downshift at high speed and you'll wind the motor up TO high when you shift down. You will either blow out the baffles or blow out the motor.
Ernie