Does the Alphard actually have soundproofing, and is it effective?

To be honest, adding those didn't make much difference on the highway [I want to be left alone]. I did add rims and a full interior, but for daily commuting, it's still okay.

I've done soundproofing, and honestly, the noise level at high speeds of 110-140 km/h feels the same. It's similar to a Cayenne.

Japanese cars generally use thinner materials, making a significant difference when they're reinforced, especially noticeable after driving at high speeds.