I had heard of someone (sorry I don't know the details) who flew a 45 sized airplane at something like 175 mph...it was of his own design and was flown with the Turbax fan.
On average, the JHH jets range from 140-160 (depending on which airplane) or so with the turbax fan. I've seen JHH airplanes with the turbax 48 setup fly around at the same speeds as other manufacturer's airplanes with the .91 sized engines.
Your best bet might be to contact larry at Jet Hangar
[email protected] . He would be able to give you the information you're looking for I think.
Chris