The 505 intake sits flat where the 504 sits on a diagonal. Thats why they give you the adapter. The jug is flat like a 505. Generally speaking. Ive heard of some 505s with the diagonal 504 style intake port. Anyways on a sparta foxi its diagonal style intake so you will have to use the adapter. You can make it face either way but you will have to do a little filing for max performance facing forward. Kit doesn't come with gaskets so you have to make them. I tried milk carton yesterday and soft seized today. Pissed. I tore it down and rebuilt today along with the clutch and its running well. I think im still under jetted at a 72 on a 16mm Dellorto. Go figure. I used thick gasket material from autozone and no leaks. I think that kit is gonna be perfect for a Foxi. Let me know how it goes.