How do I go about diagnosing the tension? I mean I can feel it by hand and say oh its not too loose, and oh it doesn't feel to tight. Is there a set in stone method to determine whether the tensioner is good or not.

Just to add, by visual inspection my belt looks excellent. But in between quick hard shifts it'll squeel. Also it squeels pretty bad if i'm cruising at a good 50+ MPH pace, push in the clutch, rev it up and drop the clutch.