I can't see there being much of a gain from an induction kit aside from it being noisy, and again there won't be a huge gain (if any) with a fancy filter; but the one thing I would recommend is making sure the filter is changed a lot more frequently than the manufacturers service schedule so that it's free of dust and debris which is the one thing that will affect airflow. I doubt they even open up the airbox until the 40k service and Diesels suck a lot of air which in turn means potentially a lot of dust!