I have used Split-fire platinums in my 16v with noticible positive results- -- noticible enought that after have a dealer service (valve adjustments, etc), I noticed that the car didn't seem the have the same "umph" and engine didn't have the nice growl that it had had. I checked, realized that the dealer had gone back to stock plugs, replaced the plugs again with splitfires, and the car came alive, again. The Bosch 4 platimums in the 16v seem to have a similar effect to the splitfires. However, on my 500E, the Bosch 4s seemed no different than stock plugs, whereas splitfires gave the engine a little more urgency ("umph"). I dunno. None of this is scientific or truly objective. But thats my experience.