Also a big guy. The same problem, and with a two different stock pans. Figured it was seat flex. So using masking tape, release agent and Mighty putty I made some stoppers to fit in the lower seat "bucket" The problem has been fixed for the last 40k. I am setting up now to do some other molding and I could mold it as well if anyone would like to have it. I know BMW should fix the problem but I doubt they will.