NEED HELP! 97 cobra

[braindead]

i have recently stumbled into a problem with my 97 cobra. i have just gone through my sencond serpentine belt and i cant figure out whats makeing the belt slip off i havent had this problem until recently...i have taken off my supercharger "ATI Procharger" because i thought the pully on the back might of seezed up and its fine, i replaced the tensioner pully and it worked fine for about 3 tanks of gas then i noticed it had started to slip off again, i put it back on and the next weekend it came off...i thought that since i have 442rwhp it might be the torque of the engine so i had it dyno tuned put under lots of stress and the new belt held up so im at a loss as to what to do because everyone who has looked at it can not figure out what the problem is and i was hopeing that someone on here might of heard of something like this happening before to them or a friend if you have ANY ideas or questions about the car please post them...until i can figure out what to do its going to be staying in the garage. thanks for everything!