Marty,
I was only overdriving the supercharger about 13% that day but that's not why the belt failed. Chris Wise damaged the belt on a water pump stud at the track because his tensioner pulley bearing was sticking. Since he was trying to beat Demmit's record I gave him the 10 rib belt off my car and tried making a pass on his damaged belt. As you can see, the belt didn't hold up very well and shredded my hood liner and a couple hoses. But it still ran a 13.3 and Chris did beat Jim that day, so it wasn't all bad.
No I didn't have to remove the upper IC tube, just the two nuts and slide the flange back out of the way a little. It wasn't rubbing, I just thought it need a little more clerance, so I ground the edge closest to the pulley down about 1/16".
David