Sorry Flash!
I have been super busy and no time for the interwebs the last couple days.
I understand about the discounted rate issue. I'm not really sure how I'll charge, but I will figure that out later on haha.
As far as soundproofing goes... It is a matter of blocking the sound frequencies that come into the vehicle while driving. You have engine roar, muffler noise, tire noise, reverberation of the sheet metal and other sound influences. My wife and I decided we are going to keep the xB until she dies, so may as well make her as comfortable as we can.
I'm going with a 3 part system.
Part 1: Constrained Layer Damper(CDL)- what this does is it stops the sheet metal from flexing as you drive and causing that reverberation effect in the car. Most people just cover the entire inside of the car with this type of material. It is not effective when used in that fashion and is very expensive. You really only need to use it on 25% of the surface area for it to do it's job. You have probably heard of this stuff by the names Dynomat, or Fatmat or any number of other brands. It is a vibration dampener and that's all it is really good for. This product is about 1/8" thick. For placement I just tap the panels and when I hear a tinny sound, I put a bit in that area to control the sound and give you that solid sound.
Part 2: Closed Cell Foam(CCF)- This is basically a decoupler between the exterior of the car and the actually sound barrier layer. it will absorb some of the higher frequency sounds, but really it mostly acts as a spacer. This comes in 1/8-1/4" thick. use the thicker stuff where you will get high traffic like in the floor of the drivers and passenger sides, where it will get compressed often and loose it ability to float the barrier.
Part 3: Mass Loaded Vinyl(MLV)- this is a super dense but very flexible layer. You want a solid layer of this product covering the entire inside of the vehicle. This is the product that does the work of actually blocking the sound. This product is about 1/8" thick and weighs in at 1lb per square foot. It is pretty hardcore and again, it is important to ensure there are no gaps in the pieces so you want to overlap and seal with a vinyl cement, like HH-66.
That's about it, gut the entire interior and layer the stuff on. This is a very basic rundown, if you would like to do more research Google "sound deadener showdown". It's not overly comprehensive, however it will help with the high level info to help you drill down as far into the subject as you care too.