TJ 4.0 cat / muffler delete

The reason I'd like to get a more deep and throaty sound is because a big jeep should have a sound to match it lol

This sounds like being caught up in fluff, just go shred some rocks and show it (or don’t and be okay that your neighbor doesn’t know what a TJ is capable of). My TJ’s exhaust is from the factory (13-14yrs old) and performs just fine. The only change I want to make is due to some contact from the tummy tuck on the front passenger Control arm mount.

My neighbors just think I drive an old POS.
 
This sounds like being caught up in fluff, just go shred some rocks and show it (or don’t and be okay that your neighbor doesn’t know what a TJ is capable of). My TJ’s exhaust is from the factory (13-14yrs old) and performs just fine. The only change I want to make is due to some contact from the tummy tuck on the front passenger Control arm mount.

My neighbors just think I drive an old POS.
Haha I'll figure something out eventually, probably just going to get a Flowmaster/Magnaflow muffler and ahh I see
 
I'm so into the Borla's because of their aggressive sound, but I know it'd bother the hell out of my neighbors lol

Well you certainly wouldn't be into mine then. Isn't very loud at all. It gets somewhat noticeable around 4000 RPM, which is what @rasband was hearing when I was cruising out of Denver at 4500 in third gear. Around town, it is pretty quiet to my ears.
 
Well you certainly wouldn't be into mine then. Isn't very loud at all. It gets somewhat noticeable around 4000 RPM, which is what @rasband was hearing when I was cruising out of Denver at 4500 in third gear. Around town, it is pretty quiet to my ears.

I thought I heard it on mosquito, maybe I just like tractors then... 🤣
 
  • Like
Reactions: jodomcfrodo
It will just sound bad. And obnoxious. And Stupid. And make you look dumb driving around. Why are people obsessed with making their stuff sound broken while annoying everyone else around?
 
  • Like
Reactions: L J
I have a straight pipe from the precats back and it has a nice deep tone that I love. At highway speeds, the exhaust quiets down after it gets hot. When I start it in the morning when its cold it sounds like a gunshot going off, so if you have annoying neighbors I would add a muffler and just delete the after cat.
 
I have a straight pipe from the precats back and it has a nice deep tone that I love. At highway speeds, the exhaust quiets down after it gets hot. When I start it in the morning when its cold it sounds like a gunshot going off, so if you have annoying neighbors I would add a muffler and just delete the after cat.
video? I'm idly looking at exhausts. I can't stand not being able to hear the Jeep at WOT. right now I'm leaning towards replacing the stock muffler with a Flowmaster 40, and then if that's too quiet ditching the Main cat.
 
video? I'm idly looking at exhausts. I can't stand not being able to hear the Jeep at WOT. right now I'm leaning towards replacing the stock muffler with a Flowmaster 40, and then if that's too quiet ditching the Main cat.
It kind of sounds like a tractor in this clip due to the camera being in front of the jeep.
 
Last edited:
You have a 1999, which has one cat with a post cat O2 sensor. Don't delete the cat, you'll throw a check engine light and not pass any emissions inspections. Those with 2000+ TJ's can delete the third cat and get away with it because it isn't monitored by any sensors. Yes, in theory you could tune out the O2 sensors but is it really worth it for the zero power gain? Not really.

Any Flowmaster muffler can be made to fit easily in place of the stock one and will be plenty loud. Banks Monster is another option although slightly quieter. These will still sound decent. Removing both the cat and the muffler will sound like shit and be very annoying.
 
  • Like
Reactions: TJRick