[Mando]

Im using one thats available through Everett Morrison cobras in the US. Its about 6-7" square but it needs plumbing. I didnt want to put one in but everyone I know with a cobra or similar open top car says you really need one, not for the screen but for your legs. Theres a picture of the heater in my gallery.
My engineer tells me Ive got to have one in South Australia to pass for rego. He told me the only way not to have one is to have no screen at all, or one of those little racing screens.

Ledge, I wish I had seen your fibreglass ductwork before getting mine. I bought my ductwork from DRB and it took a bit of work to bring them up to standard. Yours looks good from the getgo.