Can anyone tell me the best kind of wax to fill my
wings with to gain the greatest height on the pull
up?

Presumably the stuff is stiffer than water (At sensible
temperatures) so I can safely ignore those pesky flutter
limits.

And as long as I use German, rather than Czech wax,
the higher weight shouldn't cause any problems

:-)

(Thermals stopped in UK, waiting for the wave to start!)