Not a waste at all! It does make a LOT of difference in sound quality. Here is mine done in "Fat Mat", same stuff just a little cheaper.

 

I'd hit as much surface area as possible -- The whole fairing is a semi-resonant cavity -- the added soft mass of "tar" mats dampen that resonance. There's still a lot of "lost" (for lack of a better term) energy - But you'll lose some of the boxiness added by the cavity.
True - and I'm glad you find some of that stuff handy. Though I have to admit, as picky as I am about playback systems (the speaker chain I work with is worth more than my bike), I only have a very basic knowledge of enclosure design (for this purpose, the fairing would be considered an enclosure) and I can tell you for sure that HD's fairing just isn't physically capable of producing "really good" sound.

Left and right sharing the same air space is just the start. It isn't properly sealed, certainly not ported in any way that might help (if it's even possible), etc. Not to mention that it's open-air - Then put it in motion and all those "rules" change again.

If I didn't know any better (due to the rather shocking measurements I got from HD's stock speakers), they picked the stock speaker to sound decent while helmeted (and no shock, they actually sounded pretty decent while wearing a helmet). So swapping out speakers is somewhat of a must if you're looking for something "acceptable" and dampening the resonance is something that should be done at the factory, IMO.

Long story short -- It's never going to sound really nice. All you can really hope for is to make it "less irritating" and "acceptable" --

Then again, I'd sort of hope anyone buying a Harley with a stereo isn't expecting it to sound good in the first place...

 

Sorry i moved this post to this post Pollyfill or matting

 

I started using the J&M stuff when I bought a set of their speakers, I didn't really know if it made a difference because I didn't try the speakers without it. I no longer have anything from J&M but recently changed my outer fairng. It makes a difference, I bought some sound deadner to put in my new fairing, I'll be sticking wth it.

 

I have some Dynamat scraps here at work but decided I'm not going to use it. Too much added weight on already flimsy brackets. If something was resonating due to low frequency sounds, I would consider sticking it on that specific part that was the cause of the issue. Will be using sheets of polyfil around the speakers (BT 7.1).

 

I would think the foil on backing of the dynamat could cause a short some where inside
the fairing if any wires ware on it. That being said, I can see dynamat being used inside
the saddlebags with speakers in the lids, not a lot of wires there. That would also help with
keeping the beer cooler cool.

 

So, 10 years later, speaker pods, upgraded gear available from practically everyone, what are your thoughts now?

 

Sound insulation like dynamat will make the bike heavier. Just be prepared for those consequences

 

I did mine this winter. Did it help? I have no freaking clue, I did the amp and speakers at the same time.

I have always liked the product, and have used quite a few sheets of it in the past on my system upgrades in our trucks and SUVs.

I have to admit, I was skeptical in this application. I am just happy to be able to hear some tunes clearly now at 90 mph, with a skull cap on. It breaks up the long 400 miles days