Swooshing sound?

[Graham26ZR2]

My 21 gmc 1500 3.0 was totaled and I replaced it with a 26 1500 ZR2 3.0. I have a swooshing sound under the passenger seat area under the truck at times. I did notice an electronic valve in the exhaust in that area that looks like the flapper valve on the gas trucks. Could this be restricting exhaust and causing this noise? If so any tips to keep it open?

 

[Graham26ZR2]

My 21 gmc 1500 3.0 was totaled and I replaced it with a 26 1500 ZR2 3.0. I have a swooshing sound under the passenger seat area under the truck at times. I did notice an electronic valve in the exhaust in that area that looks like the flapper valve on the gas trucks. Could this be restricting exhaust and causing this noise? If so any tips to keep it open?

Tried to post a short video but keep getting the oops something went wrong error message