From his sig I am only seeing a CAI and STS as anything that would change sound, STS shouldnt for any reason. Although he mentions having a tune and thats not in his sig.
OP, is your sig updated with all your performance mods?
---------- Post added at 12:39 PM ---------- Previous post was at 12:37 PM ----------
Also, my CAI whistles, might possibly be the sound you are hearing. I mean I know you said it doesnt sound like a whistle but being that you guys have a diff engine and intake routing not to mention turbo it could be the sound. Though I can get it to whistle in all gears.
---------- Post added at 12:40 PM ---------- Previous post was at 12:39 PM ----------
OFFTOPIC: had some older guy ask me if I was turboed because of the intake almost sounds like a huge wastegate or BOV depending on how I play with the throttle