I mounted mine high in the stock spot and cut the pipe off at an angle. I like the sound and I haven't crushed it yet like I did my stock muffler
I also run a CAI and superchips. I don't think I really had any mileage or power gains, but for me the issue is keeping the engine running cooler since I deliver mail out of my JK.

 

Is anyone running just a Banks muffler in the stock location without the whole cat back piping? I just am looking for something that does not make it sound like a irce burner and will give a little more power and mileage.

 

If replacing the muffler will get a little more power and milage I would do it but a whole cat back at $300+ is too much.

 

i fitted a powerflow rear muffler only...
beautiful burble at idle...

great 'note' in first second third...

but on the highway...
i have this 'drone reverb'...could drive you nuts...

slight power increase...no change in mpg...

as for that crazy drone...
i just have to turn the music up...

 

Is yours a straight through designs or does it have a little bck pressure?

 

Lots of great points and questions made here so far, maybe we can shed some light based on the Dynomax cat-back systems for the JK that we have. The most popular cat-back system from Dynomax for the JK is our "High Clearance Rock Crawler System". For those with long travel suspension systems this is the perfect system as it removes the bulky muffler from the rear of the JK (2 and 4 door) with mandrel bent pipes and our 9" round Ultra Flow muffler. The muffler is a huge part of the system along with the tubing and bends, for both hp and torque gain as well as the sound you get. If your thinking that a cat back for this particular vehicle is going to throw you back in your seat, you'll be disappointed at most systems out there (we won't claim all as we focus on Dynomax products). 7-10hp is what we dyno'ed on our kit (in Michigan where our test facility is). That is going to be different in Colorado at elevation, in Florida with the humidity, and in California at sea level. Needless to say on what you feel, the HP and torque gain is there.

Sound.... Jeep builds their exhaust to get good flow and low noise, Dynomax (and most other aftermarket manufacturers) go for max flow and let you as owner see if you like the sound that is overall produced by the muffler/pipe configuration. Our Ultra Flow muffler is our best flowing CFM muffler in our product line, it is also at the higher end of our sound chart. Our newest muffler, the DynomaxVT is a combination of superior flow with what we call "Drone Free Performance". One issue with the JK that I think we can all agree on (not including those with HEMI's) is that we have to be "ON THE GAS" the majority of the time to get our 4-door, lifted, large tires, heavy bumpers, winches, etc with the 3.8L V6 motor to get up and go. The DynomaxVT muffler is going to be great on the interior Drone at cruising speeds that don't require your foot to be to the floor.

If interior noise makes you want to jump out of your skin, don't go with a straight through or 2 chamber muffler. If a gain in hp and torque is what your after and willing to deal with interior noise (beyond what a soft top, mud terrain tires, and just in general comes with owning a Jeep), then Dynomax has several great Cat-Back systems available. http://dynomax.com/part_view.php?sye...hed=1&x=46&y=7

Or you can build your own custom exhaust using any of our great mufflers. http://dynomax.com/mufflers.php

And yes, one reason we do offer a 90 day Performance & Sound Guarantee on all of our Exhaust Systems and Mufflers is so you as our customer are happy with your decision to by Dynomax Performance Exhaust. If what you purchased is not to your satisfaction, what ever the reason, we want you to be happy and keep you as a future customer of Dynomax on a vehicle down the road.

 

I think adding a CAI is as big a waste as adding a cat back system. Neither one will give you anything in the way of improved performance or power. Just more noise.

 

So what is the conclusion? Does it help or does it not. Free flowing or some back pressure?

 

Thanks Dynomax. I like the point that manufactureres have identified the drone sound and made mufflers that can minimize that negative effect