[adalex]

I have a gen 4 i4 with the trd muffler. I dont have any other exhaust changes, but recently when my wife sat in the back she said the noise hurt her ears. I know there's kilmat and dynamat but wasn't sure which to possibly get and where to put it to hopefully quiet the muffler noise.

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[norm356]

the problem is blocking every possible noise path, which includes the windows and through the back seat

It will be far simpler (and cheaper) to put the stock muffler back on, if noise reduction is your goal.

 

[adalex]

Well I figured more the droning noise. I thought maybe the trunk etc

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[OleAvalon]

Other than noises from your wife, did YOU hear any difference in exhaust noise while she was sitting in the back?

I'm asking because the extra... er... weight in the back could have lowered the body on its suspension in a way that made the tailpipe touch or vibrate against the underside of the car.

 

[adalex]

I dont think so not really. I was looking at maybe kill mat for the trunk mainly by the muffler and maybe under the rear seat cushion but it's on my to do list

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[OleAvalon]

If you're getting resonance and/or sympathetic vibrations across sheetmetal expanses, mat-type sound deadening will have some effect. If it's low-hertz sound from the muffler, there's not much beside high-density structures (or active sound killers) to kill that. Active sound killers are powered sound generators that create sound waves that are directly out of phase with the unwanted sound, effectively canceling it. They're going to be expensive and unlikely to last in an automotive environment.

If it's any use to you, I can post a not very good pic of the sound deadening under the back seat of our 01 Avalon, which is a Camry with more sound proofing and a bit of stretch to the fore-to-aft length of the cabin. Let me know. I'm pretty sure our 03 has even more sound proofing, but I don't have any pix of the 03.

 

[lE5QE0]

I have to agree with OleAvalon in that adding a butyl based CLD may only have "some effect". That material is good for panel resonance but doesn't do a whole lot as a sound barrier. Your car has had the TRD muffler installed specifically to achieve a certain (louder) sound. That sound is harsher and runs counter to a quiet interior. Installing a MLV barrier under and behind the rear seat may help, but that would be an awful lot of effort for relatively little return. Additionally, any gap in the barrier would negate most of its effectiveness.

Have you taken the step to ride in the back yourself? Sometimes there can be a harmonic effect only at certain positions in a vehicle. Have someone drive you around while you're in the backseat and see if you can isolate where the majority of the noise is getting through from. Perhaps you wife is more sensitive than you are, or perhaps it really is louder back there. If you do find that there is noise coming from a certain area, put your effort in based upon where you most noticed the noise.

I have done quite extensive sound dampening in my '13 Avalon (doors, floor, roof, trunk, firewall, wheel wells) and it is VERY quiet. Even with everything I've done to my car, I am certain that installing TRD mufflers would increase the noise immensely.

 

[foxtherouge]

If you're brave enough, weld a shield over your muffler. Give it space between the muffler and the body of the car. It will deflect sound waves.

 

[OleAvalon]

Okay, this is a case where He wants a beefy, muscular sound where She prefers something more svelte.

Seems to me that Tesla shows the way -- electronics + good speakers.

If I were doing it, I'd like the original of the second sound in the video above, which Road/Show calls "futuristic." It's not futuristic, it's the scream of a supercharger on top of your average 12-cylinder Packard Merlin engine circa 1944, such as you get in my favorite airplane, the P51 Mustang, In the video below, it's first heard at 1:40; again at 2:29; 3:15; and, on the ground, 4:40 or so

For you Brits out there, it's the same sound of your Supermarine Spitfire with the Rolls-Royce Merlin engine... Packard merely got permission to make the RR engine in the States during WWII. And here's your video -- don't miss the formation fly-by at 1:38 or the comments to the video:

 

[lE5QE0]

I'm torn when it comes to synthesized engine sounds through a sound system. Yeah, it has the cool novelty factor, but eventually I feel insulted by the fact that I'm being fooled into something. It's like I'm expected to be happy about being manipulated. I find it comparable to fake shift points on a CVT.

Regardless, back on topic... adalex, I think you're going to need to decide if you like the TRD noise more or if there is a compromise that would make both you and your wife comfortable. Dampening with CLDs may just be a good route for that compromise... Might as well give it a shot since it's not too expensive. If you don't like the results you can always remove it.

 

[OleAvalon]

I'm torn when it comes to synthesized engine sounds through a sound system.

Let's ignore the fact that I had my tongue firmly in cheek when I posted the Harmon idea... and that I don't know which has the more authentic sound, the TRD muffler or the vanilla Toyota muffler...

How about a dual exhaust system? Not the usual type, which is just one system for each of the banks of an engine. Instead, I'm thinking of a system that bifurcates its way into two mufflers using two controllable exhaust cut-outs. Mr. Gasket Exhaust Cut-Outs 5424

One cutout comes before the TRD muffler and feeds a parallel exhaust circuit that contains the vanilla muffler. You then insert the second cutout downstream of the mufflers, allowing the exhaust to rejoin the original run to the rear (which in many cars today then later artificially bifurcates into two exhaust tips... more inauthenticity).

It would allow dynamic tuning as well -- set each cutout to half open and you marry the TRD sound with the vanilla sound.

You could add a third cut-out to the pre-muffler setup and use the cut-out a la 1930 -- exhaust open to the air, no muffler. That might tend to set things on fire under your car, given modern exhaust temps, but for a short time, you'd have a very emphatic sound combined with an impressive light show.

 

[tedmich]

This is a hilarious rabbit hole in car "customizing/detailers" where the Mfgs of Dynamat and its brethren sell their crap for HUGE profit margins and people attempt to re-engineer the ridiculously quite cabins that Mercedes and Lexus have spend HUNDREDS OF MILLIONS building into their cars from the ground up. Thus the internet abounds with sad stories of people paying up to $10k to get their ride disassembled and add hundreds of pounds of poorly engineered hyped "sound deadening material" (usually just adhesive asphalt fabric tiles) only to be very unhappy with the resultant 3-6db of sound attenuation.

Crank up the stereo or don't make wifey sit in the back!

 

[adalex]

It was just one time because my front seat is a mess, I just didn't realize it was loud in the back. I dont sit back there so I'm just looking to make things comfortable if I have passengers

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[slavie]

There are sound deadening materials, and there are sound absorption materials. High-end luxury cars have both.

The aluminum backed butyl sheets (I used killmat - same thing as more expensive dynamat at a fraction of the cost) are sound deadening. They will reduce the vibration in the metal, that tin-can rattling noise. You don't have to cover ALL the panels with it, 20-60% of metal is sufficient to achieve all the effect you can with this material. It will definitely have some effect, but it won't solve the problem completely. I took door cars off and put it on the door skin, trunk lid, rear quarters, spare wheel well, wheel tubs, rear deck.

Then you have sound absorbing materials. These are usually thicker, fabric type material that go on top of the butyl sheets. More effective, but also much more difficult to install because they're thicker, so more difficult to fit.

Then you have multi-layer acoustic glass and other stuff that's outside of reach of mere mortals.

Take a look at an ES300 or Avalon in a junkyard. Both were upper scale cars, so you may see where Toyota placed additional insulation in those cars to give you some ideas, or maybe some parts will even fit the Camry.

Ultimately though, the TRD exhaust may have to go. Frequent consequence of having a family and having to have more people in the car that don't enjoy the exhaust as much as you do.

 

[Camreeeee]

Yall with your fancy insulation and sound deadening. Just wear a coat, boots, and gloves then put in some ear plugs.

Once I strip my doors and roof liner tomorrow there will be zero carpet, insulation, trim, or sound deadening outside of the drivers footwell (cause I'm not a savage).

I think I'm just gonna fill my door panels and b and c pillars with spray foam.

I like my interiors like I like my hookers - stripped, rough, and loud.