I know mine bellows pretty good with the window down and near a barrier or tunnel. I do have a muffler though.

 

Well just to update I finally got my cat back on and it sucks! The whistle is almost all gone and even at 3000 rpm where it used to scream now its just a low rumble. Also my exhaust stinks now. Its a really sweet smell that's hard to describe but I hate it. If you can get away with not having a cat then by all means get rid of it.

 

sure you don't have another issue?

 

Yeah, its definely the cat. I remember this smell when the exhaust was stock, I guess it just wasn't as strong with the muffler on too.