i have a greddy type s on my 3rd gen 3sgte. when i first did the engine swap and add this bov the bov was pretty loud. it always used to make a high peak pshhhhhh!!!! no matter what was the rev. now i has to go iver 3500 or 4000 to hear the pshhh and is not even loud its a lot more quiet.
is not that im worry about just the noisr but something could be getting bad with my turbo? the gauge showd that is boosting fine though.
any ideas?

free rev the engine and watch the BOV, if its opening and a rush of air comes out, then its working

Could be the valve is just barely opening for some reason. Generally there'll be a vacuum line coming off a solenoid leading to the BOV, could be the solenoid or line is cracked.

under idle, its normal for a BOV to be open just a little. its supposed to close under slight throttle and of course under boost it should be closed.

Weird it'd all of a sudden get quite though. Thought of something else, if they're like HKS they have the "whistle" or whatever you want to call it you can change out. Could be that fell out.

You probably have a boost leak. You can do a boost leak test to find out.