+1 for GruppeM. The exchange rate is killing the price now. The people saying you pay only for the carbon look have no idea how it SOUNDS. That is what's amazing. The CF looks great, but you only really understand how good their work is when you see their titanium exhaust first hand, that is a lot more impressive.
aFe is also world renowned for making intake kits, just like GruppeM, right?
It's not really difficult to use a filter that will allow more air + other stuff through to get some money from M3 owners based on a few HP. I would not use a non K&N or known company's filter on my cars.