Originally Posted by
DazC
Lee Catermole aka TiB reached a peak of 172mph on a 3.9 rear diff so they aren't that short a ratio. He will have had an 8.2k rev limit though I think.
I lengthen my ratio by fitting 19" wheels with 225/40/19 tyres a 3.9 diff will pull 204mph @ 8.2k if you have the power to pull it.