Thanks, I am really loving them.

Can't speak at all to the durability yet as I just installed this past weekend. My car lives in the garage, never sees rain/salt, is bathed more often than I am, etc... I would honestly suspect no problems though even if someone used their car 'normally'. They look/feel quite durable.

 

I was thinking more about damage to the colored surface from taking off and putting on the nut. I've had bad experience before with painted lugs and I wonder if a zinc is more resistant to trauma.

 

Really the most important aspect of the bolt is to make sure they're the proper length, and the correct seat. Porsche's use R14 ball seats. Ball seats come in R12, R13, and R14 so make sure you're getting the right one.