Squealing noise after underdrive pulley install...

[bbfirebird]

I had an SLP underdrive pulley installed on my 2000 Formula w/ 48k miles, and after it was put on, a squeaking noise has developed. It didn't start right away, it started maybe a week after I had it put on. Originally, it was only noticeable when the engine was cold, and only when the car was accelerating. Over the past weeks though it has progressed to the point where it can be heard all the time, and it is louder/squeakier than it was before. I've tried spraying belt dressing on it, which quiets it somewhat, but not much, and any benefits that it does get are gone within an hour or so. The belts I had put on were Goodyear Gatorbacks. I did notice right before I had it installed that the crank belt was .5 inch shorter than recommended. I had them put it on anyway, and it fit fine.

Can anyone tell me what this noise might be? Worn tensioner, bad idler pulley, wrong size belt?

Also, can someone give me the proper size (and preferably part number) for the belts to use with the SLP underdrive pulley?

[bbfirebird]

anyone?