How did the sound proofing go? I am thinking of similar for my series.
It turned out really nicely, I think that the silent coat and the foam were well worth the effort. Test fitting the WOR matting without them it was a little loose, now it fits snugly and doesn't 'flap' at all. I got them from Car Audio Direct, their ebay store has slightly cheaper prices and free shipping when compared to their website. I used Silent Coat Extra (4mm) and Silent Coat Noise Isolator (6mm), anything more and the matting probably won't fit. The one exception is the floor sections, which I've yet to do, but plan on using the 10mm Noise Isolator, having a look at how the matting sits over the floor panels at the moment it should fit nicely.
Noise wise it's made a massive difference. Beforehand I only had plastic door panels which meant 97dB at 60mph on the motorway! Now it's down to 81dB, so still loud but nowhere near as deafening and given the logarithmic scale quite a large reduction in energy. I made those readings with a cheap phone app so can't say whether it's accurate but the perceived difference is massive. All the top and middle clatter has gone and I'm left with the lower diesel sounds, rather how the old black cabs sounded from the back seat! Around town I can speak at a normal level to passengers with no problems. I haven't done behind the dashboard, the floors or around the rear bulkhead yet either, let alone the rear tub, hopefully there'll be some dry days this summer so I can finish the job with a Schultz spray in the wheel arches too.
As everyone else who has soundproofed their defender will attest, it will never be like a modern car, but as there isn't much soundproofing in there to start with, you can make a big difference. My approach was to use the silent coat to increase the panel mass to take their resonant frequency below human hearing and also to reduce direct transmission. Then I used the foam to reduce the airborne transmission, it also had the effect of stopping various squeaks and rattles. The WOR matting then gives it another barrier as well as being a good looking and hard wearing cover for the foam which can be a little delicate on corners. It took me three days to do the silent coat, foam and matting including removing, repainting and refitting the seats frames. I didn't test the matting by itself but it's a fairly comprehensive kit and really joins together nicely. If you were just looking to do that then I'm sure you'd notice the difference. I'm aiming to do some expeditions in the future so wanted to go the whole hog to reduce fatigue and to be able to hear the stereo I'll eventually install.
I used lots of Stanley blades to cut the matting, the silent coat and the foam (which was gloriously easy after cutting the other two!) and also a drill with various bits for the seat bolts and slave socket etc. I did try a Dremel but it seemed to just melt the matting.
All in all, definitely worth it and although it's a lot of work, you're rewarded with a tangible difference. Just make sure you have some beers in the fridge for each evening, makes it all the more enjoyable!