Exhaust upgrade opinion

I have been looking at upgrading the exhaust system on my 2010 JKU while Dynomax is offering the Spring rebate.
I'm looking at the VT Performance Exhaust Systems 38456.
I was wondering if there is any real performance gains or just a different sound.

Eugene the Jeep said:

I have been looking at upgrading the exhaust system on my 2010 JKU while Dynomax is offering the Spring rebate.
I'm looking at the VT Performance Exhaust Systems 38456.
I was wondering if there is any real performance gains or just a different sound.

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Im sure on a dyno, there is a measureable gain, but your not gonna be doing burn outs with that 3.8. Im sure it helps a fuzz but if your looking for big power gains its not gonna happen. It will however probably sound better. Depending on the model dynomax you chose, itll relocate the exhaust to a less damageable location

Bingo. On a practical level, on a Jeep, the location is way more important than performance or sound.

I've been running it for several years, can't say if it increased power but when I 1st had it installed it did seem to have a bit more oomph.

in comparison to the stock system and having traveled the same route with both on I-70, I have to say it does feel like I have a bit more mid-range power than before but nothing that'll make you go wow...it seems to hold in the powerband a bit longer for a nice steady climb.

it has no drone which was my #1 when looking at it but it does sound good when it opens up. it is tucked up better than the stock muffler.

I've been happy with it, I get ok mileage for a Jeep - but it's not all from just the muffler. I have a CAI but I'm beginning to think the stock air cleaner gave better performance. I'm hoping to install the stock air cleaner this weekend to see it makes any difference.

I also bought a Dynomax Evolution ultra flow it was at such a good price, I'm just hoping the performance outweighs the drone lol

I run the dynomax ultra flow. Much better sound than stock but can't say there are any gains with it. It does eliminate that ugly muffler from the back.

I run the dual cat-back Borla and love it. That plus the Mopar CAI make it growl!

A little while ago a guy on the trail was claiming that his new exhaust system gave him a lot more power and a bit better mileage with his 3.6. I don't know what he meant by "a lot more" and "a bit better" but I had my doubts.
Maybe he is just convinced of it because it sounds throatier? I don't know what system he put in.

Can it actually make a noticeable difference in power and mileage?

SteelBadger said:

A little while ago a guy on the trail was claiming that his new exhaust system gave him a lot more power and a bit better mileage with his 3.6. I don't know what he meant by "a lot more" and "a bit better" but I had my doubts.
Maybe he is just convinced of it because it sounds throatier? I don't know what system he put in.

Can it actually make a noticeable difference in power and mileage?

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Mileage, yes. Your gas mileage will likely decrease because it sounds cooler.

OverlanderJK said:

Mileage, yes. Your gas mileage will likely decrease because it sounds cooler.

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LOL, so there is an inverse relationship between sounding cooler and mileage. I did not know that! Does sounding cooler and more power actually correlate?

SteelBadger said:

LOL, so there is an inverse relationship between sounding cooler and mileage. I did not know that! Does sounding cooler and more power actually correlate?

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MPG and HP share an inverse relationship. Horsepower goes up, typically MPG goes down, and vice versa. Manufacturers try to keep cars running and A/F mixture of 14.7/1 to balance both. So.....a cooler sound, will most likely result in the driver revving the engine more, resulting in more power and less MPG. That's how I see it.

If you don't have a tuning program or a handheld for your specific setup, any power gains will be negligible, and may actually be worse due to not being as efficient as tuned from the factory. If you have the ability to tune so that you stay at 14.7 with your new add-ons, you can actually add both horsepower & mpg since your jeep will breathe more efficiently. Truly better flow both on intake & exhaust with a tune to match is key- any one of these 3 out of whack and chances of gain with your new growl is extremely unlikely

speed3d said:

If you don't have a tuning program or a handheld for your specific setup, any power gains will be negligible, and may actually be worse due to not being as efficient as tuned from the factory. If you have the ability to tune so that you stay at 14.7 with your new add-ons, you can actually add both horsepower & mpg since your jeep will breathe more efficiently. Truly better flow both on intake & exhaust with a tune to match is key- any one of these 3 out of whack and chances of gain with your new growl is extremely unlikely

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I have a trail dash and I installed a viper intake a few years ago.

The trail dash has preset power levels. Could one of those presets be used to help with performance.

I have tried the different power setting and really didn't notice much of a difference.

Eugene the Jeep said:

I have a trail dash and I installed a viper intake a few years ago.

The trail dash has preset power levels. Could one of those presets be used to help with performance.

I have tried the different power setting and really didn't notice much of a difference.

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The only way that could make things more efficient is if they actually tuned a jeep with your exact setup, then saved that as their preset tune. Even then it's sketchy, because every engine is just a little bit different due to tooling wear, etc, in manufacturing. The only way to maximize efficiency is to dyno-tune your jeep, or use a tuning program like hp tuners so that you can scan & save your air to fuel ratios while you are running your jeep through a wide range of loads & rpms. Then you have to calculate what to change in your computer to try to get those air fuel ratios to come close to 14.7 across the board(like a hundred individual readings); then scan again to see how close you came- can take several times, depending how much of a perfectionist you are. Unless you're willing to spend the money on the equipment yourself, then go through months of learning(maybe longer); it is probably more cost effective(and less frustrating) to take it to a pro & have it dyno-tuned. Another alternative is to call one of the companies that sell the handhelds and see if they will load a tune based on the mods you've made to your jeep. I don't know if they can, or will, do that with the trail dash or not. Obviously this will not net you the gains that live tuning will, but will most likely be much better than any pre-set power tune. You also have to remember that the engine has to be able to move the extra air through it, (and your fuel injectors have to be able to match that)or nothing you do to either the intake or exhaust will make any difference. Most factory engines are tuned pretty efficiently for what they are, because the car companies benefit from better mpg & horsepower #s with better sales. So to make a long story longer...without some engine work, you will be pretty limited on power gains you will notice; and probably won't see much more than one or 2 mpg even with pro tuning, and lucky to see anything positive with a pre-set tune.

anything is better than stock.. I ordered a spintec muffler and gunna do it myself but have a lot of experience.. its not rocket science by no means.. but why waste money on tubing when you can use parts of your existing system.


Box tuners suck and they always have.. spend some good money on hp tuners and et it tuned properly.

5280Sapper said:

Box tuners suck and they always have.. spend some good money on hp tuners and et it tuned properly.

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I completely agree with this statement, if you have a motor worth putting in a dyno...your stock jeep motor is not.