Diff ratio for bec?

[ozzy1]

Pork chop is pretty spot on with his info.
Super7thheaven has a fair bit of useful info on sierra and Granada diffs.
My experience is this.
I had a Formula 27 with a Zx9 motor in it running 195/55/15 and a 3.62 sierra diff. I did try a 3.92 and it was awful to drive on the road . Revving its tits off for no speed. The 3.62 was a good compromise between speed and acceleration and was great fun except on the motorway where is was doing about 7k for 70mph in top gear. So I would say that having a more powerful engine you would want a ratio lower than 3.62 as porkchop said. The freelander diff is probably your best cheap option really. Also I don't think you really need an LSD unless you are going racing.