Now this has been an on going problem for the past month and half. One day I was day I was driving and the belt just fell off. Now this has happened before about three years ago under GM's warranty. My car is no longer under warranty and when they had replaced it before they replaced the whole tensioner pulley assembly with a brand new belt. Now this is very odd. My car has a GM installed stage 2 kit from the previous owner, but on the work order they had installed a stock belt. Well it lasted about 30k miles and than fell off again. And now I replaced the belt with a stage 2 belt and it completely shredded after 11 miles after I went into about 5psi of boost at 3k rpms on my way back from the body shop. I than came to replace the whole entire tensioner assembly again with a stage 2 belt and it seems as soon as I turn the car over the belt falls off. And now I tried to put the stock belt on from when it originally fell off a month ago and it would fall off when I would go over 1200 rpm. I'm just stuck in confusion on how or what is wrong with my car. I replaced the belt twice and the tensioner. If anyone has any help it would be of great help.
Thank you

 

The hub for the pulley for the supercharger might be put on wrong.

 

I'm not sure that if that is it, only because it would of fell off alot more than before this happened

 

there has to be an alignment issue of the pulleys. the blower hub might not be pressed on far enough, or maybe the alternator or a/c compressor isnt bolted on correctly.

 

GOPR1022_zps9dd01283.mp4 Video by Coooooreey | Photobucket

Here's a video i hope this helps, i really need some help.

 

It might just be the camera angle but the tensioner pully and s/c pulley to me do seem like they aren't in line with each other.

EDIT - Also am I the only one who finds it odd that when it starts up the tensioner gets pulled way down.