I am having the same clunking noise on my pss10 and also think they are not firm at all even at highest/hardest settings. Maybe will go Öhlins to. will see.
07 335i AT - TD St.2 Turbos - COBB (Custom Cobb mapping by http://www.protuningfreaks.com/) - JB4G5 ISO - Okada Coils - NGK 5992 Plugs - E85 Walbro - Injen Intake - Helix IC - Snow Stg. 3 - Stett CP - AR DPs - midpipes 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - Level 10 AT upgrade - Alpina AT Flash