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Old 05-29-2008, 02:48 PM   #1
PowerLabs
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Default Adding resonators to eliminate drone?

Allright, I give up. After 13000 miles with my GHL Exhaust, including a trip across the entire country from LA to NY, I've had it! The drone is driving me insane; at 1500 to 1900RPMs, or in other word, the exact speed most vehicles cruise on the highway, it sounds like I am sitting inside a drum. It wasn't so bad when I was driving cross country because I never drove slow enough for it to be at that RPM range, but driving friends around town is downright embarassing: EVERYONE complains.
I had another car that had excessively loud exhaust after I went catless and I had a muffler shop weld in a Magnaflow 2.5" stainless steel resonator before the muffler. That quieted it down a lot and it sounded deeper and better. Could this be the solution to my problem? Would it fit anywhere, perhaps between the X pipe and the GHLs, replacing that middle junction?
Is there another solution, other than the stock exhaust?

To clarify a few things:

My car has headers (kooks 1 3/4 with dual high flow cats and an X pipe, though this is NOT relevant, other than the fact that it would be even louder without cats of course), but the GHL droned from day one, back when it was all stock minus the exhaust. The headers did not make the car much louder nor did they create the drone.
The GHLs are loud but not too loud. They sound great except at the 1700ish RPM range when they drone like nothing I have ever heard.

Last edited by PowerLabs; 05-29-2008 at 02:52 PM. Reason: Clarification
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Old 05-29-2008, 03:53 PM   #2
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resonators are designed for just this purpose.
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Old 05-29-2008, 04:17 PM   #3
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Default Resonators

The inclusion of resonators in your exhaust system might work. I assume you are currerntly using the mid pipe which came with your headers. If that's the case, you may have to modify it to acommodate the resonators if that's where you're planning on putting them. You may also want to contact GHL before you invest the time and money. I've read that sometimes resonators have a tendency to intensify the drone as they just change the RPM range where the resonance occurs. I'm not an epxert on this subject, I'm just passing some information along that I've received in the past. I know your pain. I had an H2 which I installed a Magnaflow exhaust system on. It sounded beautiful on the outside, but it got to a point that I couldn't stand to drive the vehicle. It actually started to cause headaches that went away as soon as I removed the exhaust system.
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Old 05-29-2008, 04:25 PM   #4
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Judging from my experience the mufflers control the drone. My'05 w/14336 Magnaflows droned(badly). My '08 w/NPP drones (mild) with the mufflers open but has no drone with them closed.

Sunset Orange Creations switch solved the drone; Open around town for the good sound and closed on the open road for no drone, the best of both worlds.
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Old 05-29-2008, 05:53 PM   #5
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Any other ideas? Does anyone have the contact info for GHL?
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Old 05-29-2008, 06:31 PM   #6
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You may be right about adding resonators. I have the zoomers cat back exhaust. There is a pair of resonators in the tunnel just behind the X pipe. There is a slight drone at mid revs if the engine is pulling in too high a gear. Cruising at the same rpms is quiet. It makes sense that the size and design of the resonators is important. Perhaps one could buy just the resonators and have them installed.

Regardless, good luck
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Old 05-29-2008, 07:06 PM   #7
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take a look at the corsa touring system. it looks like they have a pair of resonators added to the system. It would be something to check out. let us know how you make out
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Old 05-29-2008, 07:29 PM   #8
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Good luck and let use know how it turns out. I went back to stock to eliminate the noise.
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Old 05-29-2008, 07:34 PM   #9
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Take a look at the Corsa tunnel kit (#14166). Its part of the complete Sports package (#14167) for the A6. I had it installed with my GHLs and it decreased the drone in the usual RPM range but did not eliminate it. I ended up giving up the GHLs and completing the Corsa Sports system for the A6 with the Corsa Sports axle back mated up to the tunnel kit H-pipe.

Last edited by Bandit1; 05-29-2008 at 07:47 PM.
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Old 05-29-2008, 07:42 PM   #10
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Sorry to hear of your problems. The same thing happened to me w/ my C5. Once I replaced the obnoxious resonating aftermarket system w/ Coras, I was much happier. This problem is all too common with the C5 and C6. I haven't heard them all, but from what I know, they all (aftermarket exhaust systems) drone except for OEM and Corsa. Corsa's have a higher pitch than most of us like, but that's also the reason they don't have resonance (absence of low frequency).

IMHO, you will just be throwing more money after bad money and not fix the problem by adding resonators. If you add them, you'll likely tell yourself (and us) it's better, and then 2 mos later, you'll finally admit to yourself that you still don't like it This problem goes back to the days when the C5 was new. Other Forum members would recommend a high dollar x-pipe to those who had the same problem as you. That never fixed it. The only fix is to R&R with Corsa or OEM.

I also don't understand people saying the NPP drones (mine does not) unless they are talking about running with the fuse pulled or an open switch. NPP DOES NOT drone when operated as designed.

I love my NPP and I was also very happy with the Corsa Touring on my C5.

My advice - sell your GHL system on the Forum for sale section - you'll probably get at least half your money back. Then buy a Corsa system. You'll be glad you did.
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Old 05-29-2008, 11:19 PM   #11
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You bunch of wimps.....
I have the B & B Bullets, they are great....
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Old 05-29-2008, 11:22 PM   #12
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Quote:
Originally Posted by carlrx7 View Post
resonators are designed for just this purpose.
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Old 05-29-2008, 11:33 PM   #13
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B&B makes a PRT mid-pipe that virtually eliminates drone with their systems. It is in effect a resonator. I think you can make something like that work.
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Old 05-30-2008, 05:26 AM   #14
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do the prt's have cats? I cant find a pic. on the B&B website. if not where do the cats go? the xpipe w/ cats looks like they go right after the header.
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Old 05-30-2008, 07:47 PM   #15
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I put some 12"x2-1/2" race bullets between my LGPro headers with cats and Magnaflow muffler combination on my Z51 car and it eliminated the drone at 1500. My exhaust seems perfect now. I put them in just ahead of the turn up and over the half shafts. Local muffler shop did it. Would never go back to a stock exhaust system.
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Old 05-30-2008, 09:46 PM   #16
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Quote:
Originally Posted by PowerLabs View Post
Allright, I give up. After 13000 miles with my GHL Exhaust, including a trip across the entire country from LA to NY, I've had it! The drone is driving me insane; at 1500 to 1900RPMs, or in other word, the exact speed most vehicles cruise on the highway, it sounds like I am sitting inside a drum. It wasn't so bad when I was driving cross country because I never drove slow enough for it to be at that RPM range, but driving friends around town is downright embarassing: EVERYONE complains.
I had another car that had excessively loud exhaust after I went catless and I had a muffler shop weld in a Magnaflow 2.5" stainless steel resonator before the muffler. That quieted it down a lot and it sounded deeper and better. Could this be the solution to my problem? Would it fit anywhere, perhaps between the X pipe and the GHLs, replacing that middle junction?
Is there another solution, other than the stock exhaust?

To clarify a few things:

My car has headers (kooks 1 3/4 with dual high flow cats and an X pipe, though this is NOT relevant, other than the fact that it would be even louder without cats of course), but the GHL droned from day one, back when it was all stock minus the exhaust. The headers did not make the car much louder nor did they create the drone.
The GHLs are loud but not too loud. They sound great except at the 1700ish RPM range when they drone like nothing I have ever heard.
Corsa sports are perfect. I had flowmasters and the drone was horrible. I'm at 604 rwhp with no cats and a 3" ZO6 corsa sport system....absolutely NO drone
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Old 05-30-2008, 10:21 PM   #17
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Quote:
Originally Posted by need-for-speed View Post
...

I also don't understand people saying the NPP drones (mine does not) unless they are talking about running with the fuse pulled or an open switch. NPP DOES NOT drone when operated as designed.

I love my NPP and I was also very happy with the Corsa Touring on my C5.

My advice - sell your GHL system on the Forum for sale section - you'll probably get at least half your money back. Then buy a Corsa system. You'll be glad you did.
this has got to be tongue in cheek. OF COURSE the people who are saying it drones are talking about either a pulled fuse or a control box leaving the flap open at the "resonance" rpm. you betcha!
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Old 05-30-2008, 10:34 PM   #18
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Quote:
Originally Posted by Joe Lynch View Post
I put some 12"x2-1/2" race bullets between ...

I used dynomax bullets on my F-body to control drone. They did a pretty good job, but it does make the whole exhaust a tad bit quieter.
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Old 05-31-2008, 11:18 AM   #19
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Old 05-31-2008, 12:52 PM   #20
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Quote:
Originally Posted by VET4LES View Post
Good luck and let use know how it turns out. I went back to stock to eliminate the noise.
I agree, I suffered through drone in my c5 and c6 with aftermarket exhaust until I put stock mufflers back on and cutouts for when I want loud (and almost 10 addl rwhp).

But the resonator sounds like a good idea, isn't that what the Corsa tourings have to tone them down from the Corsa sports?
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Old 05-31-2008, 12:52 PM
 
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