Porsche 911, 924S, 928, 944, and 968 Bosch "Platinum Plus 4" Spark Plug.
BOSCH Platinum Plus Spark Plugs 4417. Platinum Spark Plug Equivalent to FR6DCPLUS, FR6DDC, FR6DTC, and FR6KDEO OR NGK BKR7EKC for BMW R1100, R1150 & R1200.
Bosch Platinum+2 Spark Plug 4305 - Advance Auto Parts