This was a thread for discussion awhile back. I didn't follow the discussion too much, so I don't know how it ended. I do remember there was concern the the pipe size on the Unifit might not be a standard ABS size, and I remember there was concern about the functionality of a modification. Might want to do a search through this section of the forum and find that thread. But, I think you'd have the best fit possible with the Vespin and 14" Unifit even if you can't modify it.