I just ordered my new z4 and a aftermarket filter is first on my list of things to do, has anyone put an aftermarket filter (cone or replacement panel) on their z4 3.0si? i was reading a different thread and someone was saying that the stock air box is different from the regular z4's. I found a new panel filter for the mz4 and it looks to be the same size and shape as the si at http://www.knfilters.com/search/product.aspx?Prod=33-2292. Any information on the matter would greatly be appreciated.