Yea my bad I guess I didn't read your post well. I think we are talking about the same thing. I call it a bung extension but all it does is takes the sensor out of flowing exhuast. It makes for in accurate readings and doubles the longevity of the sensor. Here it is http://www.exhaustgas.com/ProductDetail.asp?ProductID=1570&DepartmentID=14&CategoryID=75&RepID=&BasketID=

open loop systems, yea they work great on 2 strokes and 4 strokes. I have hundreds of hours tuning modded twin cylinder 2 strokes and 4 stroke singles with this setup. Just makes it very finicky changing alltitude when you start getting more horspower with porting, pipes, and head mods. Always adjusting fuel with controller.