I'm actually experiencing that on my truck. I had a small exhaust leak in the beginning nothing that was seriously loud or bad but just a small leak i planned on fixing it soon. Well i had started having acceleration problems and this roaring noise is bout the best i could describe it. So i hollowed out the cats still didnt fix it. Then i greased my front wheel bearings because they needed it and just thought could be something stupid still not the problem. Now when i got the truck it shifted so hard in 1st 2nd and 3rd it would almost give you whiplash lol probably not that bad but damn close. So it started feeling like it was getting worse. So found someone that had a rebuilt trans to just swap it out with a new converter. I looked for one to do myself but where i live now it would be super difficult to swap a trans out. I could do it but would not be great idea i dont like putting my truck on a piece of plywood doesn't strile my fancy of things i look forward to doing. Lol but got the trans swapped and then it shifted perfect like a new truck and then that roaring noise and my poor acceleration and performance is back to ****. Well i had enough of the exhaust leak which i felt got a lot louder than it was. I got some exhaust tape to temp fix it so i can hear whats going on and it sounded amazing as soon as i pulled out on the road and gave it gas boom it blew the repair tape off. And it dawned on me the damn muffler or something is plugged or clogged i went back put my had on the pipe by the bumper and barely anything was even coming out of it.. So now im goin to get some exhaust pipes from someone. Only downside is it doesn't have the O2 sensor hole for me to put mine in. Will it cause me any problems without the o2 sensor. I don't wanna start new problems also??