I think that the length of the inlet duct, and the shape of the bellmouth at the end are important. There is a filter that will fit, see the picture in this post: http://www.v11lemans.com/forums/index.php?showtopic=19581&page=2&do=findComment&comment=215103
This is what I was intending but it seems to me that you either have to cut the bell off of the stack in order to fit the 60mm filter, buy a larger filter that can fit order the bell mouth, or perhaps the 60mm can be stretched to fit over the bell (this would be ideal I think).
By the way, I really like the way that one is set up. Looks great in my opinion.
Mike