I am contemplating replacing my 1600 with a 2000 T4 and would like to know whats involved. In particular whether the gearbox would need replacing and if I need to modify any of the engine bay panels. I am sure much of what I need to know is scattered across TLB but I have not been able to find it yet. So grateful for any help and direction. I want some more power and to preserve Historic Vehicle status, hence sticking to air-cooled correct period engine.