Excellent information! I'll let you know what I find out from the dealer.The MPPK (M-Performance power Kit) for x35 cars (N55) included the tune and air box while using the stock exhaust. On the car that the OP is looking at, you can ask the dealer to send a pic of the engine bay where you should see the intake, new engine cover, as well as the MPPK sticker. BMW also offered a separate M-Performance exhaust for those cars that could be added with or w/o the MPPK. The MPPSK (M-Performance Power and Sound Kit) on the LCI x40 cars (B58) includes the tune and a straight piped cat-back exhaust while using the standard air box. Key features to look for on these cars would be the under hood sticker, the muffler has "M-Performance" embossed on it, and larger exhaust tips in either stainless steel or carbon fiber w/ the M logo etched on the top.
The M-performance stickers along the side skirts was a separate option when I ordered my 340 and had nothing to do w/ getting the MPPSK.
MPPK & MPPSK are M-Performance accessories installed at the port or the dealer so they would not show on a VIN decoder. If port-installed however, it would be on the original window sticker. And as someone mentioned, you can always go to the service dept and they should be able to pull it there. Maybe even go to your local dealer w/ the last 7 of the VIN and see if they'd check for you? You're not asking for the history or a print out, just what equipment is on the car.