Is the sound I'm hearing probably the turbo?

[shertex]

Original muffler on the E300 fell off. Went to my favorite exhaust place...they got me right in and installed a new muffler (Magnaflow, not OEM). As I was driving home, at around 2300 rpm I heard what sounded like a metallic resonance or whooshing of air that seemed to be coming from the front right of the car.

My initial thought was that they somehow disturbed one of heat shields and that it was now vibrating. (My heat shields are not in great shape.) So I took it back, got it up on the lift, and everything seems solid.

So my new theory is that replacing the muffler reduced exhaust noise in such a way that I'm now hearing the turbo spool up in a way that I didn't before.

Much to my wife's amusement and consternation, I'm a fanatic about car noises. I notice every little squeak and rattle.

Any ideas?