on my TT39, the high needle is about 2.75+ and
the low needle is close to whatever it was
at the factory.

It doesn't really matter what the rest of us
use. You need to be able to tune the engine
correctly. Set the high to almost 3 turns
from closed. It should idle and it should be
flyable. Once the engine is warmed up,
pinch the fuel line near the engine inlet
and start counting. You should be able to get
to about 3 or 4 before it starts speeding up
and then a moment after that, it'll die. Thats
a good starting point for the low needle. If it
speeds up immediately, richen the low end
and if it takes 5+, lean the low a little.

Then start doing some full power climbs and
see how the high needle is. You probably do
not want to go below 2 5/8 turns cause that'll
be too lean. Now go back and check the low
again annd re-adjust.