M3 6-Speed Clutch Possible on a '02 330 Ci 5-speed ?

I am generally quite happy with my '02 330 Ci 5-speed, with one noticeable exception: the spongy-feeling "self-adjusting" clutch. I had thought of an aftermarket performance/heavy-duty clutch but am afraid of the warranty implication. Therefore, I have just had this crazy idea of checking out the possibility of putting an E46 M3's 6-speed manual's clutch on my car.

Any thoughts (or insults), advices, comments will be welcomed.

Thanks very much in advance.