What did you do with your Hot film Mass air flow meter? If the new intake system doesn't have the ability to accept that sensor you probably
shouldn't use that intake system. You could do some drilling to make it work. By the way since you're running an E90 328i you're better off just
getting a reuseable drop in filter. Unless you're running your "cold air" intake from a wheel well or outside the engine bay, or unless you're running
an Arma supercharger, it's best to leave the factory intake box as it draws air from outside already. You knew this already though.
Check your mirrors as often as it takes for you to know where everyone is around you!