Strange noise under full boost

My 02 Tacoma is running a TRD Black case low boost 4.5psi supercharger which is a Eaton M68 model

The engine only has 65k miles and the supercharger has about 40k on it . A couple weeks ago I started hearing a groaning sound under full boost only and can be heard inside the truck with windows rolled up . I had the serpentine belts replaced last year with maybe 3k miles on them

Noticed the belts looked slightly glazed and some abnormal wear on them so today had them changed again along with the tensioner and idler pullies . The mechanic said the belt was slipping because of both pullies not keeping tension on the belt and both pullies were in need of replacement

On the drive home I had no issues with the belts or pullies and was feeling good that the problem was solved . I then head up a steep hill and while under boost the groaning sound reappeared . once I crested the hill the noise stopped


So what is making this noise ?? , I've checked the supercharger with a engine stethoscope at idle and no abnormal sounds can be heard

 

Doing more research , could I have a bad bypass valve ??