Just back from last weeks race meeting.
I used the spec R tb03 diff with 1000oil in the rear and a spool in front, and have to say that with the gear diff my laptimes improves 172 th of a second.
So i highly recomend the diff for racing. It is a direct fit, The only negative thing is that i had to sand/polish the outdrives, because the edges are sharp so that the blades would be destroied very fast.
The second piont, is that the gear cover has also be to removed.
If you use 46mm swing shafts in the rear, you also have to switch to 44mm.
But thats it!
Greetings Blueman