well i never did anything to my steelies unless u wanna go banded, like streched and then 60mm lower will look good and yeh the grills do just fit in but on yours like mine wen it over laps on the bonnet, it is dirty wen taken off so u do have to clean it well and polish it lol and its just a back box im getting. so u want to keep the air filter box and have a cold air feed to it ?
http://built-not-bought.co.uk/forum/viewtopic.php?f=19&t=189