Ok so the way i got rid of the drone was by unplugging the sound symposer. that drastically reduced the nasty drone noise. as long as your not flooring it the drone should be gone. when im cursing 65-80 i dont hear it that much as long as im easy on the pedal.

 

I tried that after you're suggestion on another post... At least I think it was you. It helped but didn't bring it down to where I was hoping. I end up doing a lot of cruising at 60-65, and that's where the exhaust seems to be the worst if you try to accelerate up at all.

 

yeah it prob was me ha. and hmmm i know what you mean. when the child is in the car just baby the gas pedal a lot and shift at or below 2k rpms. When im cruising 60-65 as long as im not giving to much gas its very quiet.

 

Only way you could change that noise is adding a resonator somewhere...

 

You could replace the front resonator with something else that would quiet it more.

 

Could you put something like this in place of the front resonator?
http://www.magnaflow.com/02product/displayapplications.asp?partnumber=13743

I haven't checked measurements for length or diameter, but rather using for proof of concept. Its a 3 chamber muffler with 3" inlet/outlet. My hope would be you could swap back and forth between something like this and the MBRP resonator.

 

Could you put something like this in place of the front resonator?
MagnaFlow Exhaust Products - For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles

I haven't checked measurements for length or diameter, but rather using for proof of concept. Its a 3 chamber muffler with 3" inlet/outlet. My hope would be you could swap back and forth between something like this and the MBRP resonator.

I made my own replacement for the front resonator, but there's zero room to add anything between the MBRP piece and the downpipe.

 

I can't say anything about replacing parts. But, the thread below has some info on adjusting the caps on the helmholtz to help with drone. This should at least allow you to move the drone away from the speed/frequency where you normally experience it.

http://www.focusst.org/forum/focus-st-performance/17051-focus-st-austenite-3-dual-cat-back-exhaust-review-2.html

 

Replace resonator or just add another in there somewhere.

Babies are really not that delicate you know lol. But if you're concerned just keep it easy on the shifts and when cruising just increase or decrease your speed till it goes away. My first baby rode in my Hemi Ram with side exit exhaust right behind her door, and second baby rode in my straight pipe Nissan 240 with SR swap so I speak from experience.

 

If the volume at which they scream is any indication then I fully agree with you. But you know how it goes, just trying to keep the wife happy and seeing if anyone has some good ideas.

 

The drone on 60-65mph with the MBRP does drive me a little crazy too.. the gf hates it and it's just the right tone to give you a headache sometimes. Other than that I've loved the system.

Interested to see if a different resonator helps out.

 

Weird. I just installed the mbrp cat back. And I get no drone at 65. Little bit between 2-3k rpm but it's not bad at all.


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After the exhaust breaks in the drone dies down. The only time I hear it is if my foot is on the pedal and not using cruise control or on a hill with a decent grade.

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Happy wife happy life!! I know what you mean man.

 

Also my wife doesn't mind it and my 2 year old whenever I rev the engine goes "Wow!"

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You all have me a little nervous... Ordered my MBRP today...


If you give a man a fire he is warm for a day. If you set that man on fire he is warm for the rest of his life!

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It's too quiet for me

 

Give it a few thousand miles and it quiets down. Also, as others have said, this exhaust is really throttle sensitive so, if you drive your car like you have a child passenger, then you should be fine. The rumbles are also pretty soothing. I used to take my Son, when he was 6 months old, for a ride in my 69' Chevelle; The constant vibrations and rumbles at cruise would put him to sleep everytime.

 

Finally crawled under to measure the front resonator. 21" chamber with a 27" overall length. The outlets of the resonator fit over the other exhaust pipes. The Magnaflow XL isn't made in that size. I have very little experience dealing with muffler shops. Could they fabricate something?

 

perfect time to tell her "sound deadening" is needed. and, if I referred to the baby as "it" the sound would be the last of my worries. LOL

good luck.

 

Haha we have since found out that we are having a boy. Prior to that it was awkward trying to go gender neutral.

Has anyone tried to dynamat the rear seat or hatch area yet?

 

I am in the same boat as you. We have an 8mo old and my wife can't stand the drone at highway cruising speeds. Since dynomat is meant to change the resonating frequency of the area it's installed, I decided to place some under the spare tire. If you rap on the sheet metal you will see how hollow it sounds and I felt this would help reduce the drone. While it did some, it didn't truly affect the highway cruise drone. I'm tempted to try some sound deadening (mass loaded vinyl or MLV) to see if it helps but that's expensive stuff. I'm currently researching other resonators as well and am curious if anyone has tried that with the MBRP catback. The tones from this exhaust are exactly what I want, just a little quieter.

 

I found out a lot of the noise and drone was from vibrations. I installed a set of the stiff exhaust hangers from Cobb and it made a HUGE difference. If any of you aren't running the stiffer hangers I'd suggest doing so. There is still a bit of drone on the highway at 2-3.5k but it's much more tolerable now. The gf is much happier lol.

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I was a little shocked at how loud it is as well. Just installed this morning though only have about 100 miles on it. Going to try the hangers soon.

 

Mine was pretty terrible to start but ended up I didn't have a section properly joined. After fixing that and some break in, I no longer even best it. Either that or now I'm a little deafer.

Make sure to run it and then go look at the joins to see if there is any black soot.

 

That's crazy! The video CJ Pony Parts put up on Youtube suggested to me that the MBRP was a lot quieter than the Borla or the Flowmaster, a LOT quieter. I understand drone can happen even in a quiet system, but still it's a bit disappointing. Maybe it was the camera...

Anyway, adding a J tube wouldn't be that tough, and it can be done in a way that it's adjustable. It should be possible to knock it out of that cruise RPM for less effort (and more chance of success) than replacing components.

Best of luck to you!

 

Still haven't bought the Cobb hangers but did some reading around. Read a few posts on NASIOC and they suggest an increase in drone/vibration/NVH with the Cobb hangers. Now I'm debating ordering...

 

Nope. My exhaust is quiet now since I had the COBB hangers installed, shaved down the cat hangers and had a shop reposition the exhaust ensuring enough clearance from the heat shields. Also had them tack weld all the joints.

Very happy with the exhaust now and only makes noise when I want it to.

siht daer nac uoy fi revo em lloR

 

Stupid question but is there any difference in sound between the T409 MBRP or the T304 MBRP? I was looking at this exhaust for the price point but if it's droney I may look elsewhere.

Thank You

 

Not that I know of. Either way the MBRP exhaust isn't especially loud. The tone is great and from what I've read/heard, its quiet as far as a 3" CBE goes. I'm just looking to tame it down a little bit more. Remember you're dropping the whole huge rear muffler when you go aftermarket.

 

go catless