With an oversized tensioner you get more belt wrap and therefore more surface area that the belt it touching the pulley, so less chance of slipping. A smaller belt works because it fits tighter, but a larger tensioner works better because it fits tigher AND wraps around the pulley more. Once you go down from a 3.4, then you start going with shorter belts. Assuming the stock supercharger belt is in good shape, an oversized tensioner will work better than a smaller belt.

Shawn

I used an oversized tensioner for a week, and when I put it on, the belt was VERY close to rubbing. Within a week, that $30 belt was trashed,slipping off the SC pulley, no ribs, etc. Put stock tensioner pulley back on, went with a smaller belt, and had no problems.

Also, you will need the puller to get the old pulley off, and press the MPS hub back on. Renting it is a much better idea if you are going MPS.

Yeah I had so much more clearance when I had put that belt on. But it I didn't see it strech slowly it did it all very fast.

I say go for the stock size belt and over sized idler pulley for a 3.4. But watch the clearance closely

Ed