Diff ratio????

[Russellb]

If you are going turbo later save up and get a 1.8 diff and drive shafts
the 4.1 works well but the 3.9 is nicer on the FWY I am happy with the 4.1
ratio with the STD 5sp

[StanTheMan]

The NB Diff bolts in. but its a case of bolting in the whole Butterfly Diff assembly. ( or diff casing) Also you need to change you Driveshaft & 2 half Shafts as well.

[Moggy]

I think it depends what sort of power you are going for...

I would get a 3.9 for any turbo application, however if you are going to have anything above 130-140rwkw I would suggest a 3.6. The reason I say that is because you then have the power to still accelerate well with the taller ratio and your revs at 100-110 highway driving will be much lower. I have a stock NA6 diff on my car which has over 130rwkw and I find it sits at 3300 at 100 and about 4000 at 120. This puts you right in the power band when you want to be cruising. I would definitely not go for a 4.1...

[Me]

Alternatively, you can get a Maruhamotors heat treated final drive for your NA6 diff centre which includes a pinion gear, a drive gear with your choice of ratio and a speedometer drive gear (so no guess on your speed).

[Matty]

I'd just get the 4.1

Good mix of not-too tall gearing, not too sluggish off boost, but with enough top speed for most turbos. Commonly available...

Plus, the 4.1 in an NA6 makes your speedo reading perfect, no need to change speedo gears.