I think I paid around $45.00 shipped to US (Idaho).
YS 110 at $280 is very good price. I just wish I could get one at that price.[:@]
The header that I use in the Explorer does not bind to the side of fuselage. It all depends on the width of the fuselage, but the curve of Karl's header is pretty narrow for current Pattern planes. I don't think you will have to cut the Zen 90's engine bay to install it, but not sure.

I will try to measure the header tomorrow and post here.

Ihncheol Park