1st Gear Too High

[MudRunnerTD]

changing the diff ratios won't have much top end loss mate, not the top end you are using anyway. It will increase your revs through out the gears and maybe add 200rpm at cruising why speed. This will mean that instead of sitting at 2100 rpm at 100km or so (just on boost) (The TD42T hates it here) you will be cruising down the road at maybe 2300rpm with solid boost.

The torque off the mark will be increased and the hill climbing will be well improved. I rate this upgrade for your money.

The type of upgrades that Robo has described start and $5000 but much closer to $10,000. It will be a Beast but it costs money.