Ok, I know that is a weird title, but bear with me. I have atleast 2 big holes in my exhuast that are at the top of the pipe, facing the body of the car. They are getting biger and louder. I ordered a new exhaust to take car of it. Today while driving I took it to redline, because it had been awhile, sorta wanted to self test my MAF and VIAS, and the closer I got to redline, the louder this noise got. It sounded like wind was hitting the car, you know how to faster you go the more wind noise there is, but it was comming from the bottom of the car, seemed like 1 at the resonator and 1 at the axle joint. These are both the places I have holes. Is it possible that going into the higher RPM range caused more air to go through my exhuast(which i know is true) to sorta blow out those holes and hit the underbody? It sounded kinda weird but I have no problems(SES light) except the cat-back. any input?

 

Muffler bearings are going bad..
Replace your exhaust and it will probably go away.