I have a 03 1500 with a 5.3l, I'm running 2.5" duals from engine to to tailpipes, and a 2.5"in. 2.5"out Thrush Welded muffler on each pipe. And I'm hearing this weird whooshing noise (and have been for the past couple of months) coming from the tailpipes when the truck warms up. Anyone know what's causing it to do that?

i made a video so you can hear it in the link below