Pretty much, a Coilover kit comes with everything you need, they are adjustable to your liking. Coilovers replace the spring and the shock, after lowering your car with just lowering spring in the very near future your shock/struts will blow because its so much more pressure on them. Which means your going to have to replace them. Honeslty waste of money and time. Of course after you lower your car you going to need an alignment. I would go with KW I'm extremely happy with my set, it's up to you how much you want to spend but suspension is something you don't want to go cheap on. I have the same wheel spec as you and I'm slammed and I don't rub. Oohhhh yeah my car handles like no other now, no more boat like feeling at highway speeds.
Spiike32: "I remember seeing your photoshoot pics with an M3 and was inspired to continue modding to make it look as clean as yours. "
THE TECH: "Only 335 guys think so."