I guess it depends on how extensive you want to go. I have done my 81 MB 240D body. I mean fire wall, front floor pans, pilars, back seat area and most of the rear shelf. I don't consider myself an expert at this audio stuff though. From what I read, the doors are the major area to do. From there I don't know. I would guess the trunk or hood. I haven't done my doors, as I want to R&R them and repaint the whole car. I did use B-Quiet as it was cheeper. I did read a few comparisions of other materials. B-Quiet was the only one that listed or reported thier suppression quality vs Dynamat. One comparision did a bunch of stick-ability, heat adheasion etc. All fine and good, but no measuring of the reduction of dB. I think that is the main concern or reason for installing the stuff. There was some other stuff that interested me, but I haven't looked any further into it. I do think Dynamat has a broader range of materials for specific applications. I plan to use their hood insulation/noise suppression mat or hood liner. I think there is also stuff for the roof, I plan to use.
Tom