hi all, ive got an 06 mini s that i recently put an alta 15% pulley kit on. my problem is that at almost redline the supercharger is making a noise almost like a boost leak or a belt slipping. idk if this is normal or if ive got a problem. ive checked the belt its still brand new shape and intercooler couplers are still intact so not sure where to go from here.

 

Different sounds...
So s squeel or a whistle?
Look at the tensioner on the belt... Folks sometimes use a reduction pulley on the sc, then use a belt that is too long...results in slippage or belt jumping/shreading at hi speed...
Can you read the number on the "new condition belt"?
Should be a 535 length with a 15%....

 

i got the belt in the kit from alta so there should be no issue there and its literally 3 months old now at most. it sounds almost exactly like a turbo waste gate at full boost but a 15% pulley shouldn't be making too much boost lol i dont think the belt is really slipping being that its brand new but i guess anything is possible

 

To ease the install (the 535 belt is a tight sob) alta usually includes the next longer belt...there is an old joke Alta=almost.....
This type of post is kinda common...and at 3 months timed perfect for when the belt is done stretching.....
Now if it sounds like a whoosh or a whistle/blowoff...then look around... Sc boots are common....

 

yup just looked there's is a 539 but i wish i knew for sure thats what it was, seems to me if it was slipping it would slip under hard acceleration across the board not just at high rpms. maybe i will try to get a video of it happening and post it. i appreciate the help thus far