Novak Brushless 6.5R B4 Gearing Issue

[jkonline]

I have just purchased a second hand Novak Brushless 6.5R for my B4.

The novak manual recommends a 17-18 pinion for a 81 spur in a B4. I was thinking of the 17 due to the fact ti is a smaller track with many tight turns.

However I have read in a few places that in the B4 that this does not fit and you have to use a different spur.

Is this the case and what set-ups do other people have?

Thanks