I'm not sure but heard its only 18's that have mag in them
I have 16's and 17's and they are alloy do powder coating was fine for me
Sure someone will put me right
17" and 18" are mag/alloy mix but the 18" were greater mag content over the 17" in the new style, the older version seem to be alloy - RL7's are a complete minefield - Ear's are alloy which are the sort after ones
Speaking from experience but someone will have a different experience with them