Hey NPR, I got injured in a car crash and since then a poor ride can really mess me up. The GTI on big heavy 18's, was just too harsh over speedbumps, ruts and potholes for me; even with the tyres at 33psi.
I try and always buy cars with the smallest wheels for this reason, but the GTI didn't get a 17" option in this country. so I imported some Brooklyn's (basically 17" Austin's) from Germany.
Coming straight from an Audi A4 B7 saloon on 17" AS5's, I found the noise levels comparable, so not bad for a mid size hatch on big wheels. Though the A4 also made a lot of noise on rough roads.
Comparing the Conti's to the PS4's on the GTI, I'd say the PS4's are louder on rough surfaces. Everything about them just seems a bit more focused on performance, I'll be going back to the Conti's I think, mainly for the reduced steering effort.
I find the GTI very well sound deadened at the front, but it seems like they've done sod all in the hatch area as usual. Next summer I plan on treating everything up to the back seats, as this seems to be were the vast majority of the noise is coming from.