@CarniifeX
yeah, it was pretty easy, I just covered all the metal areas on the door and un-insulated areas on the door panel. whoever designed the quick release door opener cable attachment should get a pat on the back. it's genius. you just pull this little clip back a little and the whole thing comes right off, and it goes back in just as easy. I've had a lot of door panels off cars and always break / lose something along the way. not here though.
I bought 9 sheets of the stuff on amazon for $150. I know there are cheaper alternatives for a bit less but I've been eliminating rattles with this stuff for years and I feel like its completely worth the cost.
all 9 sheets together probably weigh about 15lbs and I only used 1 sheet per door, i'll probably use another 2 sheets for the hatch and trunk. I don't think the weight is going to have any effect on it whatsoever, it's not like I'm adding a heavy sound system or anything else. and I'm always dumping more horsepower into it. the doors feel a lot like my old E46 330 doors now, not quite as heavy as an ///M3, but very solid.