DEI NA/NB chassis sound damping kit

DEI NA/NB chassis sound damping kit

Regular price $69.99 USD
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Noisy interior? Welcome to Miata-dom. This won't make it silent, but it's a huge step in the right direction. This is a custom, pre-cut (aside from the tape, which is easy to cut to length) kit from our friends at DEI that provides the right amount of Boom Mat. Boom Mat is a premium quality sound damping material that keeps interior panels from vibrating and generating noise by trapping that noise between an asphalt-free butyl lower layer and a 40 mil (.004" / .1mm) thick aluminum top skin (.080" / 2mm thick in total). Since Boom Mat doesn't need to cover the entire area to do its job, you spend less money and add less weight (6.0 lbs in total) to get the job done. This kit addresses the floor, rear bulkhead, and the various pieces on the package shelf. It does not include pieces for the doors, although that kit is available below. Includes instructions to show exactly where to apply it, and even includes a roller to be sure it's properly formed and adhered. 

Have an NC? This will fit, although the instructions are for an NA/NB. As long as you can get your interior apart and do some problem-solving, these should work fine for your NC. Remember that the bigger and flatter the metal surface, the more important it is to use this material to damp vibrations. Also bear in mind that you don't have to cover the entire surface to get the benefit. Have an ND? The same (as the NC) applies, but the ND has quite a bit of this general style of sound deadening to start off with. While this could improve things, it would likely be by a very small degree (if at all) and isn't worth the cost or complication. 

How much quieter is it? That's a surprisingly tough thing to quantify. While the decibels do decrease, it's not by much, but it's in the right range - the biggest difference is that the harshness and tone of the noise is much decreased / improved. These keep the metal from acting as transducer, which makes the car much more livable and improves the sound of the stereo - especially with the door panel kit. That's a tough thing to attach specific numbers to, but it does make a big difference to how pleasant the car is.



Ships free in the US.

There are no shipping restrictions on this item.

What does it fit?


Emissions do not apply.





Customer Reviews

Based on 4 reviews
Patrick B.
Helps a lot to quiet the car

Getting the roller through all the grooves was the hardest part of an otherwise very straightforward install process. It's definitely quieter at highway speeds.

Nice addition for a quieter car

Like Rob, I installed this kit along with the Insulation kit and door sound damping kit. Together, the installation makes my 92 a lot quieter on roads. You practically can't hear music from the outside of the car, even if you're blasting it inside. The backing on the sound deadening can be a real pain to remove, especially on a hot day, so I recommend leaving it in your fridge for an hour or two. That way the backing is a lot easier to get off. To me, the combination of mods is very worthwhile combined with a hardtop, and makes conversations in the car a lot easier to have!

Rob C.
Well Worth Doing it Properly

I just installed this in my 2001 NB Soft Top Miata, along with the DEI NA/NB Insulation Kit, and the DEI Door Sound damping kit. It is now a noticeably more pleasant experience driving with the top up at freeway speeds, for sure. Glad I invested the time and money to do the project properly. (Note: I also added UC Lite insulation in the trunk under the carpet, as well as some Boom Mat pieces in the spare wheel well of the trunk), along with new rigid Delrin door bushings.

meh / update / much better

**Note from FM: This customer submitted three separate reviews, we've listed them all here in a single review (with an averaged rating), chronologically, for simplicity's sake:

Two stars
My expectations were too high. Time investment for me was not worth the gains. And that's with a hard top, by the way. I put in the insulation at the same time.

One star
It's me again with an update after driving around for a few days. I've got some bad news. The car has a new very unpleasant drone at 2800-2900 RPM, right at 55 mph which is where I sit for most of my commute to work. The only thing I can think of is that the vibrating bodywork before the kit was somehow negating the droning frequencies coming from the exhaust, kinda like noise-canceling headphones. Now that they're no longer vibrating, I'm hearing the drone coming through. You're gonna have to trust me on this fellas; my wife is in tune with the kids, I'm in tune with my miata. I'm going to let it settle in for a while longer, maybe something will change or I'll get used to it, otherwise it's coming out.

Note from FM: This is the first time we've heard anything like this, and it certainly hasn't been our experience. David, please reach out so we can help figure out what's going on.

Two stars
much better
ok everybody just calm down. here's the update: after researching how to remove boom mat i decided that the easier thing to do would be to just add more boom mat. i started knocking on panels and found the floor of the trunk was really resonating. i bought the same kit again, and just went to town back there, focusing on the floor. things are now much better, particularly at around 2800-2900 rpm. i don't expect everyone to have my experience, it just seems like my combination of mods was an issue. FYI i have a turbo, full 3" FM exhaust, butterfly brace and frame rails. kind of an interesting unexpected result. maybe it will help someone out there.