2006 qclb with muffler, no cat. The exhaust is a cat-back system of unknown origin from the previous owner.

I have a terrible drone when towing. So bad I can't hear the wife and kids when pulling the travel trailer. I need to get rid of it as it defeats the purpose of family trips when you can't talk along the way. Besides, it's just plain uncomfortable on long hauls.

I've read a lot about the FTE resonator but I need to install a cat for emissions inspections where we are moving.

My question is will the cat solve the drone issue or am I looking at needing both a cat and a resonator?

Apparently, mega cabs have factory resonators while qclb's don't. Was the cat good enough for drone suppression or am I missing something?

Thanks,
Stew

 

I had a drone and found out it was my tires. I have to cat and it's quite as all can be. So quite I can listen to classical music on number 10 with my stock radio.

 

Thanks. Mine is definitely not the tires. It is fairly quiet when unloaded and just daily driving. When I tow though, it is LOUD!! It is so bad that when we go camping it gives us headaches after a day of driving. I gotta do something.

Stew

 

I put a 4" Manifold back on my '98, minus the cat. The truck was very loud including the drone. I added a 4"cat from an '06 and it settled down substantially. The cat didn't seem to affect power or economy.

 

I have the same truck as yours. A cat should not make a lot of difference. I replaced my stock muffler with a 36" Magnaflow and retained the cat, due to living in Calif. There was drone, but not real loud. I didn't like the drone, so I replaced the Magnaflow with a Nelson/Fleetpride 86131m. These mufflers are available at most truck parts stores for about $100.00. This muffler is huge; 51" long, 4" straight through with no baffles. It was a tight fit on my SB with the cat, but it did solve the drone problem, even when towing heavy. The exhaust note is only a little louder than stock. It should be okay without the cat. I really like this muffler. Info only, the same muffler in a 5" is 86130m.
Good luck-John

 

Did your truck come with a resonator near the rear axle?
Mine did...I have the same setup as yours otherwise, and I have no drone at all.


Edit: just saw that you stated its aftermarket.
In any case, think a resonator would help.

I don't think a cat is a very effective muffler.

 

My 6.7 had a bad drone with 4" and a muffler too. 5" cured it right away. (And it's straight pipe)

 

My truck is pretty much stock and I have the MBRP stainless steel from the Cat back.
When towing it's a little loud, I guess you could call it a drone, when accelerating but when I'm up to speed it's just like the stock muffler. I would think the cat would take care of it.

 

Last night I actually looked closer and rubbed the caked dirt off the muffler. It is a Banks Monster 9" x 20", in the stock location.

I think my problem may lie in the fact there is a 1- piece pipe, 9' long, from the down pipe to the muffler with no hangers on it. That pipe is probably creating a good bit of harmonic resonance kind of like a giant guitar string. Just breaking it up with a resonator and/or cat it might make the drone go away, in addition to the effect of the resonator itself.

Thoughts?

Stew

 

Makes sense.
Resonation is the drone that annoys...different than exhaust noise.

 

Most of the drone from the exhaust is flow related and the pipe at certain RPMs acts like a Coke bottle and you get resonance. This resonance can be controlled by pipe length or adding pulsation control like a cat or other muffler. I've added sound deadening to the interior of my 97 to eliminate most of the drone response in the cab.

Some trucks like long boxes experience the drone around the 2000-2200 RPM band while short boxes were more in the 2400 RPM range. I think the response of the floor and roof of the cab also amplify the resonant vibration.

 

Just pulled the trigger on a short FTE resonator and Magnaflow 49-State Cat. I will post back here when I get it installed and tested. Since the resonator is a well-proven device, I would like to install the cat, drive it, then install the resonator.

Thanks so far for helping me think through this.

Stew

 

Now that I have the FTE short resonator and Magnaflow cat coming, in what order do I put them? Wally can't help me since it involves a cat. I will be leaving the Monster muffler in place as well.

Do I put the cat or the resonator nearest the downpipe? Everything I've read says the resonator is supposed to go as far forward as possible but I've yet to find someone with a cat AND a resonator. If the cat is just behind the resonator, will it get hot enough to make it work as it should?

Thanks,
Stew

 

I've decided since I already have the cat and the resonator coming I will go ahead and install both. I would like to do the cat first and see what happens but time is running short before I move and I need to just get it done so I can work on other things.

I see no compelling reason not to put the cat first so I am going with that. If it doesn't work properly there's no point in putting it in at all. I'll place the resonator directly behind it where it will still be under the back seat. Though the resonator might not be at peak efficiency, I think it will be more than adequate when paired with the cat.

I'll report the results when i have something meaningful.

Once again, thanks for helping me think through this.

Stew



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If you use band clamps you can remove and switch out your components without a lot of effort.

That beinng said, I've had good luck with Walker 4.00 inch band clamps:

(These are the butt joint style)
http://www.summitracing.com/parts/WLK-33280/

or

(These are the lap joint style)
http://www.summitracing.com/parts/WLK-33224/


Not too expensive and allow you to disassemble when needed as opposed the the traditional "u" style muffler clamps which deform the exhaust pipe making it difficult to separate.