I thought this would be a good place to add my two cents. I just got my car back about a week ago after having the Stillen supercharger rebuilt.
About a month ago I started noticing the supercharger was getting louder. Since I had changed the oil about 1500 miles back I knew that wasn't the issue. But I checked everything anyway. Oil was clean and level was spot on. Belts looked okay. The pulleys didn't seem to have any wobble, etc. I wrote it off to my OCD and my imagination until about a week later where it went from slightly louder to what sounded like metal rubbing against metal. I determined the noise was coming from the supercharger itself and not the pulleys.
I parked it and took it to the shop that had installed the kit a few years prior. They confirmed by suspicions. They suspected one or more of the internal bearings were going bad. I had researched rebuild options before taking it to the local shop and their rebuild estimates where higher so I had them send the supercharger to 928 Motorsports to do the job. I called 928 beforehand and found them very knowledgeable. I did their standard rebuild. Their 1 week turn around time and rebuild cost were spot on. No surprises. I got the car back a little over a week ago and it runs like new. It may be my imagination but the supercharger feels better than new. I swear it's pumping out more power. But I haven't dynoed it to confirm.
928 Motorsports - Vortech® Supercharger Rebuild Services
Relevant specs of my kit:
46K on the car. 44K on the supercharger kit.
Oil changed every 5k.
Stock kit apart from 775cc FIC injectors.
Making about 420HP and 330TQ at the wheels.
Daily driven, never seen a track.