Exhaust back pressure whooshing noise

[StatenEye]

Hey Guys,

After installing the Megan Racing axle back exhaust on the X5M I've been experiencing a strange whooshing sound at high boost / hard acceleration. Ridiculous comparison video but it sounds exactly like this

Do we have some sort of valve that opens behind the turbo's to release extreme back pressure lol? I cant explain the sound. I installed the muffler with clamps as I don't want to weld it on until I decide if i like the sound.

I'm 99% sure there is no leak at the connection point but that's the only thing i can think of that would make this sound. The exhaust getting pushed off the midpipe and the airflow blowing against the muffler. The sound is that strange..

Other notes; I sealed the vacuum lines as the MR exhaust lack the valves the stock exhaust has.

I can post a video later but not sure ill be able to capture the sound.

Any ideas?

Thanks,