Well.. if we're worried about belt condition and slippage.. why not purchase a Gatorback belt ?? They not only last longer then original and give you the piece of mind, but as far as I know they also make shorter ones that will work with 3.4" pulleys and under.. just a thought... things that make you go hummm...
Yes, when I installed the 3.4" pulley I also installed a Gatorback belt. When I asked for the size smaller belt, I was told it wasn't available. I figured a size about 1" shorter than original or 25 mm but the next size smaller was about 2 or 3".
On the side of tensioner pulley there is a pointer and scribe marks that indicate the allowable range of operability. With the stock belt size I am still about 1/4" away from the end, as opposed to being dead in the middle with the stock pulley.
Well, I too think it'* too close to the end, that'* why I've ordered the idler pulley.