I don't think the Predator is good for any size pulley swap but I'm no expert. I'm more in favor of using a dyno tune from a known good tuner, even on a stock pulley set up.
The instructions on a Predator refering to pulley swaps is confussing to me. If you read the very first introduction in the Pred's intsruction book, it states not good for pulley swaps either a smaller upper or a larger lower. It later goes on to repeat this same deal. Then futher in the intsruction book it states that it has a tune bigger pulley swaps etc.