ditch the platinums and put in coppers. these cars like the cheaper ones for some odd reason. ngk or denso are what i found out to be the best.
as of brakes, if you do aftermarket pads, you have to put on aftermarket rotors. bmw makes their brakes out of softer material which improves braking and life. so you throw on aftermarket pads on bmw rotors, the rotors wont last the life of the pads. i liked my brembo blanks with posiquiet ceramic pads. ebc pads are good too.
I know a lot about cars. I can look at a car's headlights and tell you exactly which way it's coming