I will say that putting in some density to the floor will help soak up some of the sound. If you took a set of those heavy rubber mats and put them over top of the floor mats that come with the car std, you will find that the amount of noise in the cabin goes down.
I would say that Dynamat is good stuff to deaden the sound and you need to install it properly to get it to work right. That involves taking out the carpet that is on the floor and applying it directly to the metal floor so that the vibration that is transmitted through the road doesn't turn your car floor into effectively a big speaker.
I have used the stuff inside my home theatre in the basement. I wanted to have a movie room downstairs but found in my last house that you play anything and you hear it in the bedrooms that are two stories above. Why? the sound is picked up by the large central heat ducts and return air, and then the sound bounces the whole way through the house out to every room. Put the Dynamat onto the duct work (in my care the large return air trunk that ran through the media room) and the sound didn't propagate any further.
2018 Niro EX - Ocean Blue
GTA - Canada.