Chances are you used silicone to installed a 1G BOV to your 2G. The silicone can plug up a little secondary air hole in the BOV. The hole is located next to the main BOV hole on the mounting flange. Clean out that little hole and the chirp should go away.
The Last Word: If it's more a whistle than a chirp, it may be the infamous "boost canary", caused by the BOV opening and closing. Don't worry about it.