I went all out insulating my 88 camaro. I used Peel N Seal over whole floorpan then Reflectix on top of that.
I aint got to the doors yet, but when I take off the door panels in a few weeks i'm gonna go overboard Insulating them too.
The doors is one of the biggest places for sound to pass through.
Myself i'm gonna pull the door panel and water sheild off, cover inside of door skin, latch side, etc with peel and seal, then spray on some glue and stick Reflectix, then put peel and seal on the whole back of the door panels. I might even add reflectix to the backs of the panels too if I have enough left