hah lol. It should be possible to get an EVO 8/9 6 speed gearbox into the car. I looked into it a while ago, the evo transfer case and ACD system will need to go in as well to bolt up to the gearbox, and obviously a custom bellhouse will be needed as well.
I do think that for most people a change to the 3.73 final drive available from TRE is the best bet, it takes 2nd gear above 100kmh, you will never need to change out of 4th when going down the quarter mile, and 5th gear is usefully lower for cruising.