Is it worth the effort to install sound proof mat on the inside of the doors?

I believe so. It doesn't have to cover the entire area to be effective.

the sound deadening material like kilmat, fatmat, noico, etc that's dense rubbery material absorbs a lot of vibration when applied correctly.

it should be on the inside of the door skin, to be most effective.

RJM, yes also and easy to do. Don't worry about the safety bar if you have later doors, just get in on the big flat areas and stay about a inch up from the bottom so all water drains out. Best, Mark

I agree. I used my extra Kilmat sheets (odds and ends) from the interior to do both doors. You don't need full coverage. I just got what I could with what I had available. Makes a difference!

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I used noico it really makes a difference.

My '71 has that spray on type undercoating inside the doors. Is that not the way it was delivered?

Tom

Yes, they came with some spray-on undercoating on the inside fo the doors. But technology has come a long way- the stick-on sound deadening stuff is easy to apply and works great. Apply it to the inside of your doors as mentioned and you will be surprised how much quieter the car is. Also, when you shut the door you will hear the difference too.