I don't know how helpful this may or may not be to your exact situation, but it might be helpful in other ways.
Shortly after buying my (then) abused and worn out 31 Tudor, I started hanging out around a couple of Model A clubs seeking advice and ideas and tips. I remember immediately noticing how some Model As are loud and some are quiet, but not severely so. Some Model A's sounded like a modern Toyota while others sounded like a Model T with loose valves. Then, one night, I remember a guy pulling in to one of the meetings in a Model A that was so quiet, you couldn't even tell it was running. All you could hear was the rocks and pavement under the tires! Stunning.
Unfortunately, I didn't get a chance to talk to that car's owner, but I did speak to some other club members after that and got some good tips on why his car was so quiet. Most people just thought I was being obsessive about the noise, some going so far as to make fun of me. However, I knew by example it COULD be done. So, here's what I discovered-
1. You want a black steel Aries muffler. The stainless one has a "ring" to it that the black steel one doesn't and makes the them louder than the steel. The cheap ones and the old ones have a nice "Model A sound", but are not quiet like the Aries.
2. You want a recently rebuilt (correctly) babbit bearing motor. The motors with insert bearings are not as quiet as the babbit ones. I don't know why, and there are plenty of theories, but it is repeatably so.
3. Use the thick manifold gaskets (the mid/late 1931 type). I don't know why, but switching to the late model gaskets really do make a difference. Make sure the manifolds are perfectly faced and flush. Use muffler sealant on the block side of the gaskets.
4. Use the sealant as recommended when installing your Aries muffler. Do not use the "gasket" or the "sleeve" where the muffler meets the manifold. Just use the sealant and the "show quality" clamp.
5. Adjust your valves properly. Make sure your bearing clearances are tight.
6. Install a carburetor intake air filter. It doesn't matter which type, it seems. Just installing an Air Maze "elbow", even without the metal or paper element, will get rid of the carburetor "sucking" sound.
7. Replace worn motor mounts. The rubber gets hard as a rock over time. Using new pliable rubber on the motor mounts makes a lot of difference.
After doing all this (except for having an insert bearing motor instead of a babbit one), my Tudor is now as quiet as a Hybrid when at idle and moving slowly. It's sometimes fun to sneak up on people and hit the horn at the last second. I can actually hear the belt moving through the pulleys and the fan moving air through the radiator fins louder than I can hear the motor when standing in front of the car. Sometimes, when pulling to a stop, I have to glance at the ammeter to tell if the motor is still running.
At the rear of the car, you have to listen very closely to hear the exhaust when it's idling. If there is any street noise, you won't be able to hear your car running at all.
There IS a downside to all this. That is- Model A's have a very pleasant, distinct exhaust note and sound. Making the car "too quiet" pretty much makes this a whisper. That is, until you are going highway speeds. Then, just like any Model A, you pretty much need ear plugs to protect your hearing.
