Hello all, I just finished applying the second of 3 gals of Spectrum V2 to my Z. I've been attempting a major road noise/vib. dampening project in phases over the past 8 months, so I've had a good chance to see/hear the effects of different products. Before I applied the Spectrum, my car already had about 50 sq ft of Extreme Dynamat mainly added near speaker/sub areas and areas in close proximity to wheel noise (kicks, cubby area, trunk, etc.) The extreme did a tremendous job on cancelling just about all rattles and buzzes from the car, but did very little in terms of cancelling road noise (a major problem for me since I travel to/from work on a super loud freeway road).
Anyway, I like the Spectrum product. It went on easy with a couple high quality paintbrushes. It had no smell and dried rather quickly. It looks and feels like very thick paint that has been mixed with sand. Inspecting it upon drying I found that it is very different from the Rubbery mats I've used in the past. Unlike Dynamat Extreme it is not sticky, rubbery, gummy when dry. It has a less dense, almost foamy cross-section which I would guess is why SecondSkin says that it cancels a broader frequency range of noise.
I ended up stripping the entire car (seats, carpet, panels, etc.) and appying about 6 heavy coats of the stuff. It takes some getting used to -- putting it on thick that is. At first I was putting really thin coats on and spreading it out too much, which just wastes a lot of time. You have to goop it on a small area and then re-fill the brush and fill in another area, keeping it all thick. To do a proper job, recommend taking as many panels and pieces out as possible. It is also helpful to temp remove (or relocate) wiring harnesses, wiper fluid tubing, etc, or you will get the product all over them. Also, important to cover up non-functional holes (all over the place) with a little Duct tape first.
So, Two gallons covered both doors completely, the entire driver/passenger floor areas including under the white jute padding near the firewall & vertical wall behind the seats, and the entire inside of the cubby/glovebox area including wheel wells. Third gallon is going in trunk and wheel wells.
Putting a fan in the car helped drying times. But, keep in mind with this it is better to wait a few hours, at least, between coats. The stuff goes on Purple and dries to black. Once black it is OK to recoat. Dynamat type matting makes it a little difficult to apply the liquid since it is difficult to get it to seep into the nooks and crannies, but with a little effort it works out ok.
Once done , most of the interior of the car was liquid covered and many spots were a combination of Extreme Dynamat with liquid on top. To aid in road noise freq reduction I also decided to use various grades of acoustic foam. The cell types, thickness, and other properties of the foams were important in choosing which foam for which area of the interior.
I spray-glued a layer of Secondskinaudio's Overkill product over about 95% of the areas I had brushed on liquid. This product is a closed cell neoprene type of foam that is really thin (1/8") and bends and stretches really well to fit all the contours of the sheet metal. I used paper, marker and scissors to make templates like someone would for Dyanamatting -- Worked very well. I also glued a layer of Overkill on the underside of the stock carpet (to the areas that didn't have jute backing). I added Dynamat Dynaliner foam (semi-open foam 1/2" thick) to the two aft-recesses of the main cabin floor, and used a big square of Dynamat Tac-Mat (1/4" semi-closed foam) under the driver/passenger feet recess area.
I applied liquid behind many of the panel areas inside. Also put foam behind many of the panels.
The cubby/trunk area got a combination of stock jute/matting, Overkill, Vibramat (see E-bay), Tac Mat, and Dynaliner. Regarding foams (from what I have learned from this long painful process) a combination of open/closed (that is to say multiple layers) over of vaibration dampener/liquid deadener seems to work best. Problem is, in many areas of the car you won't have the free space to add multiple layers. Overkill by itself doesn't seem too helpful, but I noticed a great improvement when combined over Spectrum and another foam or when put in multiple layers itself. General rules -- 1) Like mat, multiple layers returns more than double benefits 2) closed/ open /closed seems to block, absorb, block, absorb, anything else seems to let too much noise pass through.
Lastly, I also spent some time liquid deadening the outer wheel wells with spectrum --very important. Oh, and I added some Vibramat under the hood and behind the plastic wheel-well panels. Spectrum doesn't stick well to plastic, although I will say I had some luck getting it to stick when I first appled a rubberized primer, then the Spectrum.
My car is much quiter now. I would say near a typical Toyota/Nissan sedan. No, it isn't as quiet as a luxury car. My last car was a Jag and it had this beat by far. But, I can honestly say that road noise has been at least cut in half and now I can actually hear the wind noise from the windshields louder than the tire noise.
Dynamat Extreme 36sq ft + 12 sq ft packs ~22 lbs
Spectrum 2 3 U.S gals ~23 lbs dry
Dynaliner 1 roll ~1lb
Tac_mat 1 roll ~2lbs
Overkill 2 packs ~3 lbs
Vibramat 1 roll ~2 lbs Total ~52 lbs
natural bristled brush 2", 1 1/2", 1"
smaller containers to pour Spectrum in
3M #90 spray-on adhesive