Blazer heater upgrade question
The trick is to find something that doesn´t trap moisture (lets the moisture evaporate) and quiets sound. My Limited has extra rubber pads, under the carpet and felt. I´ve got an extra piece of rubber, 1/4" thick as a protection for the carpet in the back and thick rubber floor matts. Helps some, but does trap moisture and will probably eventually cause rot. I cut up some old floor matts to fit under the seats.
Painting a coat of, odorless, undecoating, usually wax based, inside the doors and rear quarter panel also helps. Brush on works better than spray. A lot of work for moderate results.
I just bought a quieter muffler, the Edelrock, just got to loud with age. I can´t listen to the radio , without turning it way up.