Looking for a high speed gearbox

[JJ2]

Hello I am looking for a efficient 2 speed gearbox that performs good at high speeds and is not large, it does not madder if it is sequential or non-sequential. Does anyone have and suggestions?

Edited February 22, 2016 by JJ2

[Technic Jim]

Sariel made one in his F1 car from May last year. The link is here http://sariel.pl/2015/05/f1-car/#more-3379 and the video here:

At roughly 1:56 there is a render of the gearbox