Over the years, everyone here has pretty much agreed that the Yamaha stock belt is the best to run.
According to the service manuals:
'92, '93, '94 750's run part number 89A-17641-00-00
'95 800's run part number 89A-17641-10-00
'96 800's run part number 8BU-17641-00-00
'97 800's run part number 8BU-17641-01-00
I have also run Dayco Ultimax belts for years and have never had a problem on the trails, but I don't push it as hard as the guys who race their sleds.
Shark