It looks like it might be the same box used on the RTV. I really need to do something similar (to my RTV) to keep from buying so many dang outer filters.
I understand it is pre-filter.
What type of pipe is that?
I have an RTV also and I already modified it, this is a post I put on this forum on how I did it, this may help you, it its the same air filter housing, http://www.tractorbynet.com/forums/customization/303120-home-made-snorkel-rtv-900-a.html FYI read the owners manual and it says the air filters are washable, but raising the air intake helps tremendously. I only clean mine about every 2 months since I modified it....