I have also looked at claims on the TTR website and wondered about them.
While we do not know the exact height of the man standing there, we do
know from the website that the toroid is 8 foot diameter, the largest made
by OWL.
http://www.ttr.com/model13d.html
So I took that photo with the 55 foot spark length claim and used the
toroid to measure out some stuff. I think a spark length claim of much
over 24 feet cannot be justified from this photo. Have a look at the
photo and judge for yourself.
http://www.tb3.com/tesla/13m/13m.jpg