I'm going to try to describe this as best as possible.
I have an 04 WRX other than the EJ207 version 8 sti swap all I have is a cat back and Short ram intake. The other day I noticed the turbo not sounding normal, instead of the normal *sssshhh sound (gears 1-3 constant sound), now when in 4th the turbo sounds more like *sssh sssh sssh sssh (gear 4 not constant). I was wondering how can I fix it? since it doesn't sound like a good thing.