hi there my xr8 has a weird shift between 2nd and 3rd, but every other shift is ok, i towed a car trailer and a car the other day done about 440k with no problem,which makes me think the box isnt on the way out, seems to play up when gearbox gets warm/hot,and fast excelaration, any ideas

Dunno yet what it is as mine does the same thing.
Been doing it for 4 years now.
The S5 has a part to do with it I am sure but it may be another soleniod that is involved in the second change.