2000 Yukon slt 5.3l

[rockola1971]

Youve got mufflers installed so I doubt it doesnt have enough back pressure. Alot have deleted the cats and just have the annoying post 02 sensor codes. But the post cat O2's have nothing to do with how your engine runs. They are literally there to tell you that a cat is bad and that is it. You likely just need to get a tune. There is no way I would dump my exhaust directly under my vehicle. Thats just begging to get carbon monoxide inside the vehicle while at a stand still and idling.

 

[Rollincoal]

Sometimes the drone is ten times worse than the carbon. Only reason I think it’s back pressure is low presence of vacuum. Rockola 1971 your right though, the dumps are only temporary. I have two broken exhaust manifold bolts on driver side. Bet you can guess which ones? That’s right! Number one and seven. Don’t know if you have ever had to extract a number 7 yet but it’s a p.i.t.a. !
Just need time and resources before I can pipe it out to the back. I was running open headers for a couple weeks, no mufflers, turndowns, etc. I was bleeding from my eyes and ears. Just want to get those bolts out before anything is permanent under the truck.