Leave the OE box be or get a dci type intake, IMO drop ins are a complete waste of money. That being said, until you start pushing over 16psi or so, a dci really doesn't do squat. People are running sub 12 quarter miles with the stock box, an intake shouldn't be a primary concern. Mine was free, or i'd still be using the stock box.
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP
F30 N55 XDrive EBII