I have thought this for some time, but have been hesitant to express the issue:

I have two JKs (one as a Winter car for me and one for my HS age daughters to share). I’m usually a tinkerer, but have steadfastly resisted putting a CAI/exhaust on the Jeep(s). Reason being: aside from the debatable benefits, the sound created is disproportionate with the forward momentum of the vehicle. For example, I live at 8,200’ and much driving is straining up long grades. I would think it would be embarrassing to have a throaty roar at wide open throttle while little old ladies in stock Civics were blowing by me.

I had no problem putting a catback on my Hemi WK or 4.7 HO WJ, but they had some “bite” to back up the bark.

Am I the only one who feels this way?

 

No. Having a "go-fast" pipe that acts more like a noise maker just makes the driver look silly.

If someone could definitively prove that a CAI system and a new exhaust makes reasonably more hp, then I might be more eager to try it.

 

I agree too--especially if you use your Jeep off road. Excessive noise while driving off road only serves to reinforce any stereotypes the anti-OHV crowd has created of OHV users.

 

Ahmm... It's been proven with dyno results to back it.... https://www.jk-forum.com/forums/jk-write-ups-39/results-848/


Results:


Bone Stock = 180.7hp / 215.8tq


With a single Magna Flow 6” x 18” muffler
Single Exhaust System = 194.3hp / 231.3tq


With MagnaFlow + AEM Brute Force Intake System..
Single Exhaust System with AEM intake = 202.1hp / 234.6tq


Single Exhaust with AEM intake and Jet Performance Stage II chip

Final Results = 213.9hp / 243.3tq
Overall Gains = 33.2 HP / 27.5 TQ



Also there was a big gain in HP/TQ between 500~2000rpm where it matters most (for offroading anyhow...)

 

Here's a question.... Are the vehicles Auto or Standard? I have CAI's and Magnaflow catbacks on both of ours. 1 auto and 1 standard. I feel the difference more in the stick than the auto. But also both are failry new (under 2k miles) and I expect them to waken up here shortly. Unless you are fording then its always good to give the motor more air.
Also The smaller magnaflow gives you some sound but nothing embarrasing.

 

I'm with you on the noise/annoyance vs performance gains, if any. That link leads to tests demonstrating a supposed 18% gain from just a muffler and a filter, which is hard to swallow, without any other real changes. A free-er exhaust is usually worth a little, but not a tremendous amount, at the expense usually of annoying noise, droning, and if the cat is removed, not passing emissions tests; and most modern vehicles have plenty of intake capacity, the filter and air box is usually not the limit. Either the JK intake and exhaust are horribly bad designs, which I doubt considering the supposed baseline dyno run was about 0.8 hp-cubic inch, not bad; or there's some serious optimism in the later dyno runs. A dyno can be fooled, and the link also indicates that there were some problems with the calibration.

I spent a few decades in the sports car world where we will do about anything to find a few percent hp on a normally aspirated engine, and here's some guy claiming huge gains with Pep Boys add-ons. I don't think so. DC's engineers are not stupid; they won't leave horsepower on the table like that.

If I could have 10 hp and still have a water-resistant intake and a quiet exhaust, for a reasonable cost, I'd be on it. Usually, the aftermarket exhaust, "performance" chip (often just a resistor to fool the ECU into thinking the intake air is colder than it is, so it'll run richer), and K&N-like filter just adds a foolish and annoying droning sound and looks stupid; think riceboy Civic with a body kit.

 

As long as we are talking about this, does anyone have dyno results for just adding a K&N filter in the stock box.. The opening for it is in the same place that the CAIs end up so I don't see where they are getting any more cold air than the stock box. And they would be much more prone to suck water than the stock box.

As far as exhaust,, I hate noise, and the fact is a good free flowing exhaust does not have to be loud.. Just because no one bothers to make a decent one that is also quiet just ticks me off.

 

I feel you dude!

This might help.

At the beginning of summer, I installed a GIBSON cat-back on my 4-DR.
Drove to the beach the next day.
4 hours of torment!
The engine was a little more responsive, but the drone at highway speeds, and the vibration drove me nuts. It sounded like a crappy '94 Civic.
AAHHHHHHHH!

Got home, pulled it off, sold it on EBAY.
With hesitation, I decided I would try again to upgrade the exhaust.
Enter the BANKS Monster exhaust.
Very subtle tone! In fact, I can barely hear it over the AIRAID intake.
Replaces the stock set-up to the y-pipe.
Was it an upgrade?
YEP!
I don't put too much into those "dyno" results, but BANKS doesn't make garbage, and I definately can tell an improvement in overall power.

Don't be discouraged. A mellow sounding, power upgrade exhaust is out there.

Hope that helps!

 

Don't know about a JK airbox specifically, but from the overall size of the filter element vs the engine displacement and rpm, the stock box is probably not limiting, nor is the stock filter for that matter; the K&N drop in might not breathe any better than a paper element. On Miatas, my fave, an open K&N cone makes no actual difference (just a perceived one from the extra noise--"it's making more noise, I must be going faster!") over the stock box and filter on a late-model.

 

Hmmm, yes. I figured if I made an inflamatory comment like that, someone would rush to publish some dyno results.

Just saved me a search. Thanks.