Aftermarket Tensioner?

Anyone have any success with aftermarket tensioners for the p600b setup? I am having difficulties with boost. I only make about 7 lbs with a 14 lb pulley on my 95 mustang GT. (347 with holley intake and AFR 185's)

I pulled that lousy stock K&N off, and put a 9inch one on. I also run a Goodyear Gatorback belt and have a cobra R hood which lets in cooler air, but i cant seem to get the boost where i would like it. (10 + lbs) Ive got a ton of belt dust all over the brackets and blower itself, so im assuming that belt slippage is the problem here.

Any help would be awesome. Thanks folks.

- Jon