Exhaust drone and resonator use

I have the same Dynomax SS catback, I think it is #39447. The drone at 1300rpm under load in my 09 DC auto prerunner is uncomfortable. And i like louder exhaust! The rest of the time it sounds pretty good. I added Dynamat extreme behind and under the rear seat storage compartments to try to get rid of the low frequency drone. This made only a slight difference.

I contacted Dynomax by the from on the website and the reply email said:"Thank you for your inquiry for Dynomax Exhaust. We appreciate your
interest in our products.

In regards to your request, you can add one of our Resonators to your
system, I will turn down the Exhaust Tone and it will keep the Flow... we
have two options... but they are Aluminezed steel and the numbers are
#24215 which is 12" in the shell and 16.5" overall.. or the #24236 which is
18" in the shell and 23.5" Overall.. both of them 2 1/2" Inlet and Outlet
as the #39442."

Let me know how the super turbo works out for you. There has to be a way to get a good sounding exhaust and good flow without the deafening 1300rpm drone.

 

It's good to know that I'm not insane... at least in regards to the drone.

I've received conflicting replies from Dynomax. I first filled out the form online and after no response, called Dynomax. The woman on the phone tried to steer me towards the Super Turbo and when I asked about a resonator she told me that there would be no guarantee and that a resonator may in fact just shift the drone to a different RPM. A week later, the email guy responded with a similar response that you received.

All I can say is the resonator did very little if anything for the drone. It seems to have made the exhaust sound even deeper which just fuels the drone.

I did call Jegs today and their customer service is awesome. They are sending out the Super Turbo with a shipping label for me to return the UltraFlo.

I'll let you know how it works out

 

I was looking at the Dynomax catalog online and noticed that there is an ultrflow muffler that is 6 inches longer (part #17513) than the one that comes in our kit (#17219). It looks like it would just fit in front of the hanger at the rear of the muffler. (have to cut out some pipe). I am waiting for a reply to my email to Dynomax. Hopefully somebody there will know.

 

I don't see why it wouldn't work unless the clamp/hanger in front of the muffler wouldn't reach far enough forward to clamp the muffler to the pipe. But the guys at Dynomax would know best... except for the resonator advice they gave me but that was after the fact. I should be able to install the Super Turbo Saturday if all goes as planned, we'll see.

 

Sorry for the delay. Wife got back from Iraq sooner than expected so i haven't spent much time online the last couple weeks, let alone working on the truck. BUT, I just got her back from the exhaust shop and I am absolutely jumping for joy right now.

To recap, I'm running K&N CAI, DTLTs & Magnaflow cat-back. Performance was great and the sound outside was amazing - loud and throaty. But the drone in the cabin was unbearable. The sound was normal at most RPMs, but between 2500 and 3000 it got really, really annoyingly loud - as if it had hit some magical resonant frequency of the cab. It was the worst when driving uphill in that range. My first attempt to fix this issue was with sound deadening. I did the WHOLE cab - every inch. This made everything quiet EXCEPT the drone so it actually seemed louder afterwards. I then heard about resonators and did as much research as I could on their use in taco's, (on which there is very little information, hense this long post). I settled on the Vibrant Ultra-Quiet and had it installed today



I picked the truck up tonight with little optimism. I mean, if the sound is coming from the headers, how can anything downstream have a major effect? Dudes I am telling you this thing is a wonder. I drove the long way home and found as many hills to climb as I could. Accelerating uphill through that once nasty range of 2500-3000 RPMs, the volume of the exhaust was perfectly steady every time. No spikes. No swells. Driving under overpasses with the windows down showed that the sound outside had the exact same beautiful throaty quality, just turned down a notch or two. And I noticed absolutely no decrease in performance. This product has far surpassed my expectations. If you have DTLTs and a nasty in-cab exhaust drone, stop your search right now and buy this: http://vibrantperformance.com/catalog/product_info.php?cPath=1021_1033_1055&products_id=46

 

Sorry, I missed this update. I have a 6-speed. No Idea how the Vibrant resonator results may differ for an automatic. Sorry you're still having problems. I know how much exhaust drone can suck.

 

It's great to hear that you fixed your drone problem. I only wish my drone was higher up in the rev range and could have been cured by a resonator. I really liked the Super Turbo sound but as you know, that drone is a deal breaker.

Thank you everyone for your help and hopefully this will come in handy for someone else down the road.

 

Okay, I just got a reply from the tech line. I think they misunderstood that he number I referenced was a bigger muffler not the other cat-back system. But the other part?? Tell me what you think.

From the TA-walker tech line:

"the #17513 kit flows and sounds as the 39447.. the only different between
these two kits it's the material... Stainless Steel for the 39xxx and
Aluminezed for the 17xxx kits... under loaded trucks need more Motor force
to compensate the extra weight... unfortunately the kit will not decrease
this undesired sound... adding a resonator can be a part of a solution...
I'll add: put the Max PSI allowed on the rear tires to get less friction
and if you can, get some coil over units or air shocks that are able to
handle the extra weight... again, just to keep the rear end in good
position so you can have less friction on the tires. Thanks"

 

Methinks that guy had a wee bit too much egg nog???

I think he got confused with the part number you gave him. Dynomax made a cat back with a 17xxxx number for the Taco that was aluminized but they replaced it with the 39xxxx stainless models.

As for the second part, he attempted multitasking without the cranial capacity for such a task. He was probably answering multiple emails at the same time and didn't have enough practice with the cut and paste.

I'm positive you can use a larger muffler with our kit but you'd have to cut more pipe. Even if the clamp/hanger wouldn't be able to reach the new front of the muffler, you could always run out to the auto parts store and buy a $2 clamp and leave the current hanger/clamp where it is. As for whether or not it would cure the drone, I have no clue.

Part # 17287 is the 20" shell Ultra Flow and #17748 is the 20" shell Super Turbo. I really wish Dynomax would have done their homework before selling the kit as it now stands. But after reading the response you received from their "tech support", I can now understand.

Dynomax has a 90 day return policy so if it doesn't work, you should be able to return it. Either way, good luck and please keep us informed if you go for it.

 

3 Month Update.
Ok, so there is a little in-cab swell in volume in that same 2500-3000rpm range. It's possible that it was there when the resonator was first installed and I didn't notice it because I was used to a much louder drone. But I did some critical listening as soon as it was installed and I don't remember any swell at all. It's minor, but it's definitely there now. I still love the product. It's still MUCH better than without it, but I feel like the effectiveness of the resonator is starting to wear off. Is this possible? Is there any reason when a resonator breaks in and accumulates a little build up that it wouldn't work as well? If so, what could be done?

 

I just installed my ultra flow muffler (sized to best match the stock one) and the drone doesn't seem to bother me a bit. Maybe the size makes a difference? Also on their site it has a new muffler coming out soon that is supposed to eliminate drone while cruising.

 

I don't know much about your resonator, but I do know that most "glass packs" that people use for resonators and mufflers wear out over time. It's a possibility that your resonator is just an expensive glasspack that's losing its effectiveness.

For what its worth, nothing worked for my low rpm drone so I sent it back. Neither the super turbo muffler or the aero resonator helped. It may have made it even worse by quieting everything except the drone. Long story short, I got my money back on the catback but I now have a resonator junking up my garage.

Live and learn.

 

I think you may be on to something. The Dynomax catback had a smaller (lengthwise) muffler. I was just sick of messing around with it so I sent it back.

 

I have this one http://www.summitracing.com/parts/WLK-17512/

If that helps I don't know, but it's working great for me.

 

Just started researching these problems you guys are having, anybody have installed a borla cat-back, and where was the resonator installed,. Would like more of a high pitch than a lowwww roar. sound any suggestions?

 

How's the drone now? I just bought a MBRP exhaust and the drone is horrible I really wanna sell this thing to someone else..is the resonator doing as well as it was when you got it? If this thing works I might consider getting it to quiet down the sound.

 

I just installed the URD DTLTs, and I already had the URD y-pipe and TRD cat back on the truck. The drone is pretty bad. I'm glad I found Abe's post about this and adding the vibrant resonator. Ordered one today. Hope that helps as much as Abe says it should.... We shall see

 

The 1GR is a 60 degree V6. That gives it smoothness. It also yields more even exhaust pulses. Because of that it will be nearly impossible to get that deep, non droning sound.

90 degree V6's have uneven exhaust pulses that can help with the sound quality of the exhaust note. But 90 degrees is not ideal for a V6 because it's not inherently balanced.

Toyota went for the smoothness of a 60 degree V. So chasing that perfect exhaust sound is a loosing battle

 

Update:
Added a 18" vibrant large diameter resonator and it has cut the rasp and drone down considerably. Still pleanty loud, but I can now travel at highway speeds without getting a headache.
My build leans toward performance over looks or sound, so I wanted to keep as high a flow as possible. I would go quieter, but that would just negate the $500 I spent on the headers in the firstplace.

 

Where did you install the resonator? I have a similar setup with the URD LT equal length headers, URD Y pipe and URD catback and the drone and rasp is pretty bad under load. And it’s pretty loud for my taste so I’m not too worried about the resonator being overkill.

Did you get a hissing sound mainly under load after putting on the headers? When I rev it in neutral and let my foot off the gas it almost sounds like a blowoff valve on a turbo. I’ve read about this happening on other cars after installing headers but I was wondering if that happens to Tacomas too.