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Trials and Tribulations of 11Hemi's Custom Exhaust

2024 Views 9 Replies 6 Participants Last post by  klement1
Hello to all,

So I purchased an 11 Laredo X Hemi a few months ago. I wanted to give it a little rumble so I brought it down to the local exhaust shop to have some changes made. Here are my experiences with the different setups we did:

1st setup remove muffler, leave both stock resonators in place:

Quiet at idle with a good gurgle. At partial and full throttle, a very loud and pronounced twang to the exhaust note. Huge loss in torque, MDS not functioning properly. 16 mpg hwy. This was way too loud and I did not like the fuel economy dropping from 21 mpg. 9 out of 10 in terms of volume.

2nd setup replace resonators with Magnaflows:

Recommended to quiet Jeep by shop. Much quieter at idle, gurgle is reduced as well. Partial and full throttle is still loud with a little more torque but nothing compared to stock. MDS still not functioning properly. Mpgs are around 17 hwy. 8 out of 10 in terms of volume.

3rd setup put center muffler back in:

This is the point where I stopped paying for the work and the shop was working to make me happy with the setup. We put the center muffler back in and left the Magnaflows in. Let me say, if you want power, this is the setup to have. With stock being a 4 out of 10 in terms of sound, this setup is a 6. The Jeep goes like a scalded ape. Plenty of tire squealing and just absolute performance all around. Easily knocked a half second off of the 0-60. Feels like sport mode in auto. Sport mode is just nuts. After I got done flogging it, I did a test on the fuel economy. Highway mpg driving like the other two setups netted 14 mpg. MDS still not functioning except on coast and going downhill. Absolutely horrible fuel economy but awesome performance.


I brought the truck back and had the stock resonators put back in. I am back up to 21 mpg on the highway and nice quiet performance. I do not know the science behind the way Jeep set the engine and exhaust up but in my experience, fuel economy is best with the stock setup and the stock setup only. I ate the money I spent on the custom system and called it a life lesson. I did not find on here a good writeup of what happened when you replace the different parts of the system. Had I found one, I may not have done what I did. I figure I would write my first post here to maybe save somebody down the line the aggravation of trying to find out. Happy Jeeping
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You did not say what you replaced the front muffler with. If you removed it and just replaced it with two pipes, one for each side, then yes, you killed the scavenging effect of the exhaust by going with a true dual set up. This kills the torque produced by the engine and kills the fuel economy as well as makes it very loud.

On the other hand, if you replaced it with an X pipe, not only would you still see the MPG's, you would likely feel the increase in torque from the scavenging effect, and a decrease in sound due to the sound waves bouncing off of each other as the sounds passes through the x. The stock front muffler provides the balance between the right bank and the left bank like an after market h pipe, but does not flow as well as an x pipe.

I just had the resonators on the rear removed and replaced the 4" resonated tips and left the front muffler in place. The sound is minimal on the inside, and noticeably more outside. It sounds great and I still see the same mileage and torque as before.

BTW, I have an 11 Limited 4x2, 5.7 Hemi.

Hate that you spent all that money to find you liked it stock best.

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My guess with the mileage drop, is that after you begin to hear how beautiful the Hemi sounds when accelerating at moderate throttle input. This leads to more rapid acceleration just to hear the motor, which leads to a drop in mileage when you hear almost nothing. lol just a theory, but so true for me!
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