I've seen mx bikes beat streed rods alot...
I used to live in Lander wy... one of the guys there had a BEE-U-TIFUL 1970 GTO.. 400, blower, narrowed rear, slicks... just all around a sweet ride set to roll stoplight to stoplight....
and I watched him get owned 3 times in a row by a Yamaha YZ490.. one of the old air-cooled ones even.....