believe it or not I have something similar on the back of my tunnel.......its called a tuned pipe. I have it setup to stick direcly out of the back and lowered it down once parralel to the cavitation plate to see what would happen, I was able to trim it up to the max and it wouldnt blow over, it would get up in the air and then it would hit my muffler and drag the front end back down......not the best thing it the world for racing but it looked cool. ;D
Herb Stewart told me after he saw it do that, it reminded him of the old days when he ran a Magic pipe he had a flat plate on the bottom of the pipe for the exact same reason.....a wheelie (propie) bar.
~James