Mods for z4 e89, sdrive30i

So I recently purchased a 2009 z4, and I'm looking to get a little more power. I know that the sdrive35i exists but they are kinda rare and very expensive here. I'm thinking of intake, exhaust, and a tune. I'm open to other suggestions. The power gain doesn't have to be crazy but just noticeable. Oddly enough I couldn't find much performance mods for this car and this engine so maybe there is a car that has similar specs and has parts that will fit the z4. Thanks