Right now the Kilmat was $34.99/box and I used 11 boxes total, saving the rest of it for other projects like my rattling AC in the house. Before my dad died he put a much larger unit than the house needed so it struggles to force all of the air through the tiny vents...I need to run bigger hoses to all of the registers, but those are expensive and I already have the Kilmat so....lol.
The Siless 157mil foam was $57.95/box and I used 6.5 boxes, could have just used the rest of the roll in one of the doors.
The Soundsulate 1lb MLV was $235 for a 4'x25' roll and I had maybe 10sqft leftover just applying it to the floor and rear doors for the test.
Soundshield WrapIt foam tape was $29.99 for 1 can with 2 rolls inside and I used the whole can.
Grand total was $1,054.88. Yes it was expensive, but considering the reduction I feel like it was totally worth it if you plan on keeping your truck for the long haul.
As far as what is NEEDED, that's entirely subjective. The Kilmat will kill panel resonance, that's it's designed purpose. If you do 100% coverage, then it acts as a full barrier as well. It's also zero gap because it's squishy rubber which still helps. The issue is that it's only designed for certain frequencies which is why I say it helps that it's full coverage using squishy stuff. The foam and MLV are used for frequencies, but work best as a full set. Personally, I would not do it without the foam because of the other added benefits. The temperature control is sooo much better now and it really makes you feel like you're in a soundproof box versus just having the Kilmat. I've ridden in a truck with just butyl rubber (can't remember the brand he used) and it was good, but nowhere near as good as mine.

On the panels I did 3 surfaces, but you should only do 2. The vehicle has 2 metal shells, inside and outside. So I did the inside of the outer skin, the outside of the inner skin and the inside of the inner skin. You should aim for the outer skin (this is the roof, floor, outermost part of the doors and walls) and the inner skin (the stuff that the trim attaches to. I had planned to have extra material just because I wanted to stuff as much as I could everywhere. Considering I used 11 boxes with my method, you could probably get away with only using 9-10 boxes. Technically, you are only supposed to need 25% coverage with the butyl rubber to achieve 80% volume reduction. Going 50% is supposed to get you to 90% reduction. Going 75% is supposed to be 93% reduction, etc. Basically by the numbers alone it's diminishing returns. Think about it this way - I placed Kilmat from wall to wall inside the doors. I could have just placed 1 sheet in the center of the outer door skin instead of the 3.5 sheets to get full coverage. On the foam you still need the full 7 boxes to do what I did. If you avoid stuffing the cavities like I did then you could get away with 6 boxes of foam. Either way, 100% coverage is what you need to aim for with the foam just because of how foam works. Just don't put on the stupid DVD frame...lol

Time wise, I went slow because the Corps destroyed my body and it took forever with injuries plus I had to stop working and put enough stuff back in to drive it around. I also did this completely on my own with zero help just to prove that it could be done without help if anyone else had to. This is totally doable over a single weekend for someone that's not injured. If you can get one person to help out you could do it in a single day no problem. The only thing you might want to get someone to help you with for all of 10 minutes total time is getting the headliner in and out. Since it is a single piece you have to slide it to the rear a few inches and then drop one side to the floor so you can pull it out the rear at a 45 degree angle and then find a place to store it where it's not going to bend in half. Getting it back in was a PITA because I had to use the MLV's cardboard tube to hold up one side while I located the pushpin holes and line everything up. It's doable by yourself, but I would recommend just borrowing someone for the headliner. Making sure you have the right wrench for the rear bolts of the middle seat will also save you a lot of time as it easily took 20 minutes per bolt using a 19mm at a funky angle instead of having the right 18mm. If you can find it, a micro ratcheting box wrench would be best. Or just notch the seat frame...but that's more time added.

 

Didn't see your post until now, but yes I definitely addressed all of the stuff you listed. That Siless closed cell foam is amazeballs! Yes, it does get compressed near where everything gets squeezed back together, but it's not fully compressed 100% everywhere and is doing an amazing job. I didn't take too many pics of the rear AC, but I did replace all of the garbage foam except for the diverter door on the inside because it was still stuck on there really well. Not the best sealing foam for sure, but it's not broke so I didn't futz with it. I did replace the foam on all of the ducting pipes and added new pieces for the lower vent tubes as there wasn't anything there and it's a nice tight compression fitting. I also used silicone to seal the headliner duct all the way around. It's a new headliner from a junkyard, but it was in amazing condition and had the hard molded duct on it. For some reason my ducting was missing....not sure how, why or who would have chosen to do that.

I do have plans to fix the weather-stripping for the doors, just not sure what route I'm going to go yet. I don't really like the idea of adding a second weather-strip to the door itself, but I might go that route in the end.

You are right, butyl alone isn't the trick, it's the whole package. Only regret is not pre-planning for extra foam in the walls and doors. That's the whole point of this write up, I wanted everyone to know - in one spot - just how much material you can actually add, where it's needed, what practices work the best, cost, etc. The foam is the best noise damper, but it's useless without the butyl. The butyl is great, but only takes care of a small portion of the greater problem. Add them both with MLV and now you're cookin! Another 2 boxes of the foam into the doors and walls would have been the best, I would have also added it to the backside of all of the trim panels as well since that is just more negative space that could have been filled.

 

You didn't get the 2nd row seats to slide forward to reveal the bolts. At first I was cussing Ford out too, until I realized that I could just slide it forward and it gave me complete access for the impact wrench. Here is the video I used that showed me how to do it.

Impressive job overall on this project. I give you 10 Gold Stars.