Thats because nobody carries the correct size tensioner pulleys for the SC, they are slightly smaller, but you can get by just fine with the replacement ones readily available at Autozone or any other parts stores, no problem.
The only trouble I ever have on mine is when the supercharger is really boosting the pulley will slap the AC bracket and digs grooves into the pulley, but it did that with the stock size anyways. Need to get some MP tensioner springs to make them stronger.
Yeah .. if you cant figure out a simple thing, just give up. Thats what I always say. LOL
Take it to another mechanic, ie. this one here