Let me qualify and quantify what I posted earlier.

In my MkIII Supra Turbo, I chipped out all the tar mat sound insulation, ditched the ac & stereo and the fluffy sh*t on the backside of the carpet, then reinstalled the carpet only.

That, in combination with a fabricated parcel shelf in place of the rear seats (which were inaccesssible due to racing seats and 5pt harnesses) was enough to lose over 200 lbs. Highway noise rose by only 6 dB at 75 mph to 85dB total.

And it looked normal.

That said, you're definately right on CF doors and hatch; I just wanted to add some perspective to what started out as a rather vague question. The only examples of CF doors I've seen were for FD RX-7s...