I'm not going to answer for nalc, but IMO, the best approach to reduce in-cabin noise would be to install MLV on the doors and on the floor from the firewall back to the trunk. The roof doesn't really let in much noise. The biggest contributor to road noise, aside from your tires, will be wind/car noise from the windows. You can't get thicker windows...

Wow! Lots of work and lots of pics! That's awesome man! Props to you for providing so many detailed photos. How is the road noise now that you've finished doing the soundproofing, did it go down considerably? I've done this in the past two cars I've owned with dynamat extreme and dynaliner on top of that. I always did it because I did dB competitions. I pulled my three L7's and the three Kicker 1200.1's from the '12 Civic Si I traded for my BRZ, I would love to put at least one L7 in the BRZ, but I'm kind of hesitant on adding any weight to this car at the moment, it just doesn't have the torque and acceleration that I am used to (turbo K20 and turbo K24 Civic's), any additional weight I'd be afraid will slow it down too much. That and I'm not doing sound comps anymore....but I sure miss the bottom end when listening to music, the BRZ just doesn't seem to have anything under 1000Hz with the factory stereo!

You must be kidding. I dunno about the BRZ, but my FRS w/ the 300W Pioneer HU definitely extends below 150hz.

In your acoustic measurements, were they simple SPL or did you do any frequency response measurements to see what tonal ranges were improved?

Even if your app wasn't calibrated for absolute SPL, the relative measure is probably valid if made under the same driving conditions on the same road with the same weighting.

As an educational point, a 10dB change does not equal ten times the level. A 6dB change in level (if broadband) will be perceived as half as loud by discerning listeners (i.e. musicians, hi fi enthusiasts, and audio professionals). Some of the general population will not notice until the change is 10dB.

All of that aside, I commend your efforts to make your ride more pleasant and perhaps more kind to your ears over time. Planning any long road trips? You'll probably feel less fatigued with the quieter interior. I agree, that reducing the wind noise would be a nice bonus as the higher frequency tones are what typically contribute to listening fatigue.

The 70lbs added is fairly evenly distributed, so you probably don't notice it terms of handling, true? I find that with about 140lbs of road salt in the trunk, the front end would start to feel light, but with only 40lbs, it was not noticeable.

I see you're in PA. If anywhere near Philly, I could help you with the audio measurements.

its the metal on metal contact between the mirror that slides off the bracket on the windshield. what i did was just put a sliver of electrical tape between them and now no more rattle! just both sides where it slides on the bracket.

Yeah, I'm in Delco but I travel for work a ton. Maybe if you're around in September we could do a better calibrated comparison. I added pieces gradually (spent something like 2 months on this project, going one section at a time) and I don't know anyone else with one of the twins, so I really don't have a good back to back comparison, I just know that I would get fatigued and have a headache after several hours of highway driving before, and now I feel fine. I don't notice a handling difference, but I also switched to crappy winter tires midway through the project. At the end of the day, I really don't notice a difference between handling with one passenger in the car and by myself, or between a full tank and an empty tank, and both of those changes are heavier and disrupt the balance of the car more than the sound deadening. If anything, it might help the balance, because all of it starts aft of the firewall and goes all the way to the trunk. The center of mass of the sound deadening is definitely aft of the center of mass of the car, so I'm probably a bit closer to a 50/50 front/rear mass distribution compared to an unmodified that's (IIRC) a little front heavy.

That sounds like fun to do an A/B comparison since both cars are otherwise stock. I'm around all Summer and can probably organize this on most weekends (unless we take a family trip). Usually, I will need a week's notice sort out the schedule.

Allegedly there's a KOP area group that meets up at the AMC near the mall, but I haven't managed to swing by there on a Monday night (7:30) to see if they are there. We have a few FRS in the KOP area.

My office is down in Delco, so we aren't' too far from each other. The test wouldn't take long to setup if stationary. When moving, that's a little more tricky.

For a simpler method, you can download Signal Scope for iPhone from Faber Acoustical. It's a good spectrum analyzer FFT and should be calibrated for any generation iPhone. Not sure if they offer an Android version. If we configure the FFT the same, then we can capture screen shots under various driving conditions.

Studio Six Digital offers a low cost SPL app that can be calibrated and used to compare SPL with various weighting. So long as the calibrations match and the mounting method is the same in the vehicle, then the comparison is easy and valid.

With the FFT app, similar comparisons can be made and you also get spectral information (which frequencies stand out in level).

By moving your FFT to different parts of the car, you can track down specific sound level changes which might indicate other places to add treatment.

I had the rear of my car stripped should have added some while the interior was out.

nice write up and pics

Beautiful work and superb documentation - thanx so much for sharing this. I know a lot more about my car now!

@ck-GT86 @Jolaessss @themajesticone

Man, that must have taken forever to do! Too much work, as I don't mind the road noise. However, I'll be favoriting this for the headliner and the trunk portion.

holy moly! awesome DIY. I've been sick of the noise level so wanted to see what everyone else did. I consider myself patient, but damn! I shall start ordering!

I have an odd question for you. I had done similar DIY back when I had my Mazda 3 along with painting and doing so many other stuff. After this massive changeover I found the windows to mist a lot more on the inside. I was unable to find the root cause of this since I had done so many things at once. Maybe somehow I blocked the air passage to the air duct in the rear bumper, not sure.
Have you experienced anything like that?

this may be a stupid question, but could the window deflectors help with the noise coming from the window?

Need some advice please.

I wish to accomplish 2 things:
1) insulation on the roof so that it doesn't sound like a tin can when it rains,
2) insulation on the wheel wells to reduce tyre/road noise

I would like to know, will CLD tiles do the job? Or do I need something else?
From what I know all it does is add weight to change the resonance frequency of the sheet metal correct?

Any recommended brand of CLD tiles?

Also, anyone have pictures for installing sound insulation on the wheel wells that I can refer to for DIY?

Thanks a lot!