Quickshifters?

[BikerBoy]

I use a Translogic QS4 http://www.translogicuk.com/quickshifters.htm which is top shelf stuff and has its own independant ecu so wont affect your Mt4.
They also make a powershifter if that's more your thing http://www.translogicuk.com/powershifters.php

Pingel air shifters are another good choice going by what others have recommended in the past http://www.pingelonline.com/air_shifter.htm