HF, that tension level sounds about right. As mentioned....they really don't stretch so caution must be used on initial setup. I know member Rambro is posting that he thinks his RPM belt "killed" his alternator and now he's also lost a metco idler....not sure what happened there, but be careful. You want the least amount of tension possible while not exhibiting any belt slip.
I've not had any issues in 2 years now, same belt. Same size I ran before with standard Gates (751). I think that whipple adjustable tensioner is a good item with the RPM giving you the most adjustability instead of just "hoping" the traditional snub idler is going to work for a given size.
Intervention302 probably has the most time with that belt.....he was the one that prompted me to try one two years ago. Maybe he'll chime in and give a long term update.....
Thanks for chiming in brother. I've been doing a lot of reading about the RPM belt lately and I've been keeping my eye on it for the past couple years.
Figured I would give it a try, everything I've read by you and others has stated the tensioner load is critical so I'll be keeping a close eye on that. I have the Metco double bearing idlers so I'll make sure they're all tight while I have the belt off.