I happen to be doing this to my Mach 1 right now. I recommend Noico from Amazon. They have 80 mil black, silver, or 50 mil with red lettering Noico I don't like. There is probably cheaper if you keep looking. Butyl is pretty much all the same, Dynamat is just the "pay for the name" brand. Some people complain about foil thickness, they are dumb. Its just there to keep the sticky side down. Tape the edges with aluminum foil tape if you want or are going to see them.
You need a roller, the cheapest is fine. A rubber mallet is optional.
As for how good it is, my car is about as quite with just this stuff in as it was with carpet, open cell foam, and the factory insulation, & I'm not done yet.
Make sure there is NO moisture under the butyl, & that the product has full surface contact. They use this stuff to keep water out of basements around here, it will keep water out as long as there are no gaps. If water does get in it will stay in worse than the factory tar.
Next layer I recommend closed cell foam (CCF), do not use open cell foam for anything but padding. Second Skin Audio sells non-sticky sheets, or Noico sells sticky but thin sheets. Third layer mass loaded vinyl (MLV). This is pretty must the best three things you can do to keep sound out.
Note: Butyl is about about .7 lbs/sq ft. MLV is about 1 lb/sq ft.
Some of the stuff I used, I don't sell any of this.
Butyl:
http://a.co/1WK9U2F I'm using about 3 boxes for full coverage minus roof & doors.
Roller:
http://a.co/hNZoNg0
Tape: http://a.co/2PwPP4p
Mallet: http://a.co/eDudiYk
For Fabrice: Amazon.de really only has Stinger Roadkill, basically as "bad" as Dynamat. Noico comes from Russia though so maybe you can find a dealer.