New Belt Slippage on 5% overdriven supercharger

I just bought a Gates K080392 Belt (factory replacement sized for 1994SC) for my supercharger that I have a 5% overdrive pulley on. At 14lbs of boost, I get audible belt slippage and the boost drops to about 12lbs.

What would be the best replacement size belt to stop the slippage?

Thanks

Belt Slippage

I am not sure about the belt you will need, I am using the stock belt on my 95 (JK8-401) I bought at the Ford deler with an ASP 10% pulley without any problems. My car hits about 14 pounds as soon as you hit the throttle, by 3 grand it has the gauge pegged and stays there until I get out of the throttle. I actually bought and tried to use the belt you have with my stock pulley and it was to short to go on so that is why I went to Ford and found out that stock length for the 94-95 is 40 inch.

K080390 From Carquest Is 1/4" Shorter Than Stock, And Reduces All Slippage. I Paid About $15

Thanks...It worked excellently.