Muffler delete thought?

[jeeplib05]

You’ve seen what we said so do what you want
It’s your Jeep not ours :gr_grin:

 

[HoosierJeeper]

Don't cut the cats off. It'll run like crap.

 

[u2slow]

I ran a Flowmaster knockoff for a while, drone was so bad that you couldn't talk to anyone with you at highway speed
Switched to a REAL Flowmaster, was worse than the knockoff after about 5-6000 miles.

Odd. We have over 50,000km on the Thrush. You can make it loud... i.e. accelerating hard, engine braking... but at highway speeds its fine.

 

[tjkj2002]

Now the liberty's have 2 cats. I was considering cutting it right before the cats and doing a dual exhaust straight pipe. And yes there's enough room.

First it's illegal,the check engine light will turn on,you will get terrible gas mileage(way worse then your getting now),and if you sell and the new owner(does not matter if you trade it in or private sale) lives in a area that requires emission testing you are 100% on the hook to make it pass emission testing since your the last owner.


My KJ has the MagnaFlow ultra flow race muffler,very loud and sounds like a old mac truck at full tilt on the highway but silent as can be inside as long as the windows are rolled up,roll them down and no stereo in the world can be heard with the engine at 3000rpm's.

 

[tommudd]

Now the liberty's have 2 cats. I was considering cutting it right before the cats and doing a dual exhaust straight pipe. And yes there's enough room.

Please do not, all kinds of reasons not to, besides losing power, using more gas, sounding like crap, illegal and many other things

 

[BillyG]

I have to ask because I am a new Liberty owner, but why would removing the cats give you bad gas mileage and poor performance?

I put a bell-mouth downpipe with a high-flow cat and had the engine tuned and I gained a ton of power and did not lose any mpg's (250 hp and 300 ft-tq at the wheels). The downpipe eliminated the 3rd cat because of the length but it was a 49 state street legal pipe because it could still pass emissions. I still had a cat, but it had much better flow.

Is it due to the drastic reduction in back pressure? I am not advocating deleting cats just curious.

 

[tjkj2002]

I have to ask because I am a new Liberty owner, but why would removing the cats give you bad gas mileage and poor performance?

I put a bell-mouth downpipe with a high-flow cat and had the engine tuned and I gained a ton of power and did not lose any mpg's (250 hp and 300 ft-tq at the wheels). The downpipe eliminated the 3rd cat because of the length but it was a 49 state street legal pipe because it could still pass emissions. I still had a cat, but it had much better flow.

Is it due to the drastic reduction in back pressure? I am not advocating deleting cats just curious.

Any vehicle sold in the USA and model year 1996 and newer have to have at least 1 monitored cat per bank.Delete those monitored cats and the PCM will detect it and turn on the check engine light and put it into "cold" start up mode to protect the engine since it can not properly judge what's coming out of the tail pipe.

Cold start up mode is a rich state reducing power and increasing the fuel used.Plus the reduction in back pressure robs low end power on a "stock" tune meaning you have to press the stupid pedal more to get going thus using more fuel.

 

[BillyG]

That makes sense. Thanks for the info.