Another 130i joining the group..
As for mods for the hatch, not really much you can do unfortunately or fortunately whichever way you looked at it.
Exhaust - BMWP (Awesome noise and no drone )
Intake - BMWP kit comes with KN drop in filter ( Awesome Looks, but Pricy, but can just get a direct drop in KN pod, ALL LEGAL )
- for the best price on BMWP parts.