alan, u might want to try asking someone who has used 912 b4, and that would be kenny59.
but as for quiet tyres, it does make a difference. I was on stock tyres first, then Michelin Preceda, then Hankook V8, the noise level has a drastic difference. Then went onto RS2, my god....the noise level shot up, then try S1 Evo, phuah....big world of difference again. Then now using V12, the noise level is noiser than the S1 Evo.
The SSW rims I've seen are mostly heavy, because in Thailand, their roads are pretty banged up. Alot of potholes. When i drove to Bangkok, i had the "pleasure" of experiencing their potholes. I even stopped at 1 rim and tyre shop in Hatyai, and realised that most, if not all the rims were solid, heavy types. But i realised that those rims were suited for their type of roads. You get a lightweight rim with low profile tyres there, they are as good as goners.