could this be because of my gm bcs?

 

Loud high pitched noises in boost are usually caused by boost leaks.
Are you still getting full boost? Might want to stay off boost until you get it figured out...if you have a big leak you might be working your turbo too hard to achieve full boost, which is bad for the turbo.
The GM BCS just controls boost in a different way than the factory BCS so it shouldn't make any weird high pitched noises. Mine just clicks like mad.

 

its a leak

that or vtec

 

VTEC is always the culprit

 

check your uppipe gasket.

 

ill have to check it out tomorrow. ill see if i actually hit full boost. the squeal is definitely noticeable though.

 

 

i wish it was vtec

 

does that squeal sound like a supercharger because that what mine did on my 04wrx untill i replaced the gaskets for the uppipe and downpipe. than it dissapeared...

 

Sounds like a exhaust leak.Check/replace your gaskets man.
Also I hope your turbo hasn't bit the dust.