I added a lot of sound deadening to my '21. I used an app on my phone to quantify noise reduction, but it didn't show a huge improvement. When it rains, that is quieter. Noise from outside the van, it's quieter. I believe most of the noise comes from the road, and even with foam pads and carpet, it's still noisy. The noise is my strongest complaint about the Connect.
When traveling, I often have the "belly" filled with gear, and that makes a significant improvement in noise level. I call the footwell of the second row of seats, removed from the cargo versions, the belly. Stock, the cargo version, at least mine, have openings between that hidden space, the belly, and the drivers compartment. So road noise from the belly is piped into the driving area. I've read the passenger versions are significantly quieter, but have never ridden in one to know.