My buddy has a stock predator. He bought a yoshi full exhuast for it. We raced a Raptor with pipe k+n, jetting, +4 swingarm, high compression piston, cams and ported head. With the predator stock the Raptor beat him by 6 bikes lengths in a 330 ft run.

After piping the predator and jetting we let them run again. The difference in the same length run was cut to 2 bike lengths. I was very impressed with the Yoshi pipe. I think with similar sized riders the raptor would have won by a larger margin. Predator rider 165lbs, the Raptor rider 350lbs. But over all I was really pleased with the simple bolt on.