Well, blow me down !! (so to speak).
If I ever get my car thru rego, I will put a pressure probe near the intakes to see what happens over the speed range with the standard MK1 rear clip.
My suspicion is that the fan-assist might be a help off the line, but might "get in the way" at higher road speeds.
I can see some intersting problems with mixture on a carb setup, but things might be able to be tweaked on an EFI ?
Kind Regards,
Peter D.