I had my shop install an Underdrive pulley and now on start up it squeals loudly for about 10-15 seconds and then clears up. Anything I can check? Maybe tensioner needs adjustment?

 

There is no adjustment. The tensioner is always applying pressure to the belt via a spring turn around his axis. If your belt is new my guess is there is oily mechanic finger prints on it ;-) You better take a good look for the alignment of the belt rollers and tensioner. May be it is out of alignment.... Or worst, the belt is not route properly which I saw in a previous post.....