I have recently purchased a 1996 M3 with a ERT supercharger package that includes the powerdyne supercharger on it at an auction. The kevlar belt was broken when I bought it so I had the unit reconditioned. It lasted for about 30 miles then it broke again. I replaced the belt again and the same thing happens, it only has 6 pounds of boost so it is not spining too fast. It does have a bosch blow off valve but I dont know if I need a better aftermarket one. Can anyone help?

Dunno why the belt is braking, but the bosch blow off valve is fine for your setup.

Did you replace the bearings as well when you replaced the belt?

Pehaps that might be your problem. As they wear out they will get out of round and cause some issues. Check ebay for cheap rebuild kits.

Not certain on the bpv, i'm not running one on my setup at the moment.

Powerdynes are notorious for this. You would be better off returning it to powerdyne and switching it out for the updated charger. This will allow you to run more boost that 6 psi. The mustang guys had major problems with these even before they were used in a BMW application. You think they would have fixed it by then.

does the supercharger has holes on the top of it?
You might need a complete rebuild if it keeps doing this.
while powerdynes has a higher rate od belt failure, it is my experience that they are quite reliable, at least the version2 ones with holes on top.

u definitely need to change the bearings inside which cause the belt to roll off. buy the rebuild kit on ebay or use one of their associated rebuilders who will warranty blower for another year. good luck . i had the powerdyne unit for 7 years not one problem from Dinan but i am now upgrading to the RMS stage 2.