Okay boys and girls, I have started the killing noise project. I did not post this in interiors as the trunk, doors, and under top tray will be treated.
I wanted some additional canceling of noise when the top was up. Top down, who cares? For stretches on hot, noisy freeways, top up is nice but there is a fair amount of noise. Looked into it and this is what I did:

I ordered 50' of B Quiet Ultimate for the resonance barrier. It was less than Dynamat but actually ever so slightly better across the temp/db level reduction. Its a quality butyl with suspended (means no smell) asphalt for mass with aluminum backing. It was easy to cut and apply. I had a roller but did not use it. It was 70 degrees here in Sacramento. You only need to apply 25-35% coverage to be effective. You can see I did not go nuts in covering every inch as some other posters have done. The bang for the buck comes from the acoustic insulation.

From my research, it became apparent 3M makes the best material: Thinsulate. It is effective, lightweight, hydrophobic, cannot mold or mildew, compresses easily, and is easy to install. The secret is in the fiber size. They precisely make the fibers 1/4 the length of problem noise wavelengths to transform acoustic energy into thermal energy. The non spun material dissipates heat instantly. This is what Mercedes and Acura uses in their production cars. Problem? Its not sold to the public. Hard to find. $$$.

I emailed 3M and wound up communicating with the guy who services Honda! He determined I was not a competitor and just a guy doing a DIY on a Honda S. He sent me a big box with 3 varieties of Thinsulate for nothing; the quid pro quo is I send a nice letter to him (to Honda) demonstrating the install and how great Thinsulate is. He was very generous as you can see with my lab guarding the box.

I only had an afternoon to do some of the soundproofing as I am heading out on a 9 day trip up the coast to Oregon and Washington. I did the trunk and under top tray area. I will do the doors, under the carpet, transmission hump, and behind the seats when I get back. More later in a couple of weeks.

I pulled out the liners and what little insulation Honda had. I used that as templates. I put down the B Quiet and then a variety of Thinsulate. When you cut it with scissors the edges can weld together for a finished look or pull it apart for a fluffy edge. Better performance from open edges. What you see took about 3 hours. Have not driven it to see what the difference is.

 

Lookin' good!

If you're passing through Medford and see an AP2 Suzuka, that's me

 

Best noise reduction I had was putting on the hardtop. Night and day difference, and when paired with a good sound system (Focal's and small sub) the noise is pretty much gone other than the RPM drone on the highway.

 

I don't doubt that. When I put the top up, I notice a lot from behind the side window. I am going to experiment with the Thinsulate and attach in places to the top. Its thin enough to fold with the top. Just the sides, maybe the back, not the overhead. We shall see. From what I have experienced and what others have reported, the lions share of noise comes from under the pax seat and behind.

 

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Looking forward to hearing your results, would have been cool to see what the db level was before the changes were made.

 

maybe too late for a proper experiment -- but they make apps which can measure sound and give you a number back in DB

would be neat to see the improvement

 

Looking good so far Cosmo!! Waiting on results.....

 

Looks great so far! Can't wait to hear your results. I've noticed the largest amount of noise came from the tires and the engine. I will be doing something similar with the top tray and doors. Some rattles are starting to occur so I'm on the hunt for them first when time allows.

Any chance your source willing to sell the thinsulate to some s2ki members?

 

They do not sell directly to consumers. (3M) They sell to installers and the guy I worked with is exclusively Honda. They did provide, as I mentioned, free sample. I have seen some of the Thinsulate on eBay.

 

Great job. I plan on sound deadening my entire car too, especially the floor and wheel well. Trying to make my car as quiet as possible.