Had a magnaflow on for last year.... Relocated under rear seat. It was making floor board super hot so I took it back to muffler shop. He looked underneath and noticed the 4 catalytic converters and suggested I just take the muffler off altogether... So I agreed. I now have no muffler at all, sounds great and jeep feels freed up... Testing mileage right now but I am 100% sure it will be higher...

Don't know if it will pass inspection... Should I would think... But It is a big difference over what I had....

 

I think you may get some codes from you computer and i don't think you'll pass any inspections.

 

depends on local laws.. I did the same, works fine on my TJ. It wont throw any codes, unless you remove the cats and if you do that, weld a new bung on top of the old one. Moving in out of the flow.. oops I didnt say how to cheat.. lol.. its not hurting anything and if you had a magnaflow (see straight through) your MPG probably wont increase much if any. Love to hear a sound clip of the 3.8, the 4.0 sounds evil.

 

A lot of people don't realize how much noise the cats take up.

 

Its 2 cats then 2 resanators. I ran without a muffler for a couple of months and gained 1 or 2 mpg but I ended up putting a turbo pack under the drivers side infront of the axle. There was a huge power increase between the 2. With no muffler more mpg but lease power, but with muffler more power and about 1 mpg difference.