I'm not sure how many spots you'll be able to stuff 3/8" of that stuff behind/under. But if you somehow pull it off, I'd expect it to be deathly quiet and awesome.

I plan on pulling out all the factory padding. For whatever reason it all smells like ass so its not a hardship to replace it ;)

I replaced the vapor barrier on my doors with this stuff. Made the speakers sound a whole bunch better.

How much material does it general take to get maximum coverage in the miata? I am talking about everywhere including the trunk.

I ended up using just over 50sq/ft of dynamat, and I covered just about every inch of the inside and doors. everything except the trunk. Same goes for the foam stuff. Didn't see a point in doing the trunck since I completely blocked it off from the cabin, just seemed like a waste

There's loads of info out there on sound deadening, and it can be done for fairly cheap if you don't mind it being a little 'ghetto'. The best way to do dynamat is to only put on as much as you need since it only stops things from vibrating. The real quietness comes from the closed cell foam or mass loaded vinyl, which you want everywhere you can stuff it.

I know it's frowned upon to do things cheaply here, but I've seen people do roof flashing and yoga mats and the results were better then you'd expect.

We do cheap shit all the time. There is a difference between being cheap and being stupid.

I think something that would make the hard top more effective is adding some kind of layer between it and the car. I don't feel like the seals that come with it are sufficient enough. :2cents:

Nothing wrong with doing things on the cheap.

I happen to think that $50 for 50sq/ft of dynamat is reasonable.
Same for closed cell foam.

$100 bux and a relaxing day of straightforward work later, and you have yourself a much quieter and "plush" miata :)

I think for my car the main issue is squeaks/rattles, not the overall noise levels. I'm going to be extra careful when going back in with my new dash to make sure nothing can rattle, then maybe add some dynamat strategically to help the chassis. One of my main annoyances is actually due to the hardtop and my non-HT harddog bar, it loves to rub on the hardtop where the two corners are on the bar. I was thinking a proper foam or something, and then bolt the hardtop on SM style. Not sure on that yet, though.

A huge amount of the noise in my car with the top up is generated by the wind coming underneath the seem on top of the windshield. If I pull the top down really tight by hand while going highway speeds the noise cuts down significantly. I am not sure if beefing up the seals or tightening the soft top latches is the best way to fix this.

Hey, this is the place where we buy knockoffs of knockoffs of Honda IMs and weld them to the runners of the stock IMs rather than pay for a custom one. Just because we don't recommend AFPRs and other bandaids doesn't mean we're not cheap.

The seals collapse and/or lose some resiliency over time. There's a trick on M.net where you stuff some of that foam caulk backer rod into the hole. This makes it seal much more tightly, eliminating leaks and wind noise.

For me, the hard top on my NB reduces wind noise, but seems to make the engine noise more intrusive. That may just be that I can now hear the engine more with the reduction in wind noise :) I run the hard top in winter mostly for better rear visibility with the huge rear window. In summer unless it is raining the top is down so I have great rear visibility, but I hate driving with the soft top up.

Keith

I have to agree with this. I don't seem to get much noise from the trunk. The big magnaflow is extremely quiet and muffles sounds very well. The noise I'm encountering now comes from the engine bay. Anyone wants to chime on where to place some insulation to quite down the engine bay from the cabin?

I'm gonna pick "firewall for 500" alex

Well yeah, I guess what I would like to ask is if anyone has experimented on that particular area.

Firewall and trans tunnel as far back as your wallet will provide material to cover. I'll be using this: Floor & Tunnel Shield II - Heat & Sound Insulation 050501 | Design Engineering, Inc.

Kinda like what the 949Racing guys did with Crusher, but more:

https://www.miataturbo.net/attachmen...ine=1377575825

We have a thread about this actually: https://www.miataturbo.net/diy-turbo...t-cabin-74625/

Exactly as E02k said. I lined the transmission tunnel and also the drivers side I lined with koolmat, dynamat, closed cell foam, and MLV. I put real padding on the back of the carpet as well.

Should be damn quiet and hopefully no heat will be able to soak through it.

The hardtop makes a world of difference.

You don't need to add expensive dynamat all over a vehicle. Dynamat only reduces resonant noise in smooth panels. Using it for weight is silly.

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This guy used to have a breakdown of who made the best materials (which used to be SecondSkinAudio down here in Tucson) but now he sells his own product and his "less is more" philosophy. It makes sense, and would be 10x cheaper than dynamatting a full interior.

I would have loved to buy products from him in the past when I was doing my sound deadening, but after 5 emails and no response I got sick of waiting for him.