I have the same problem, mine beats on metal like crazy and I was looking for advice on that too. Any suggestions. I believe it happens only when the car is really low to the ground and the nut of the strut meets the strut mount when going through bumps with low speed. Probably some rubber or some Teflon tape?
Pending Current Projects - Full White LED Interior(done)/ ZHP Suspension & Ground Control adjustable coilovers(done)/ Black CF window trim wrapping(almost..)/ ECIS CAI filter replacement(done)/ Sprint Booster(done)