Well today I tried it on some crossed up grass ditch stuff, enough to give the lockers a try anyway, and I'm pretty happy with the engine at low rpm then. Unfortunately when I reversed it into the garage today I was forced to use low range on the concrete or it wasn't going to make it without frying the clutch, luckily my driveway is straight.
I will ring the dealer on Monday and see if they can check it out and reflash the chip if necessary, it's only got 500km on it so far. There's got to be more bottom end horses somewhere, my brothers V6 Commodore can reverse ok into my garage. It seemed to stall more often today about 4 or 5 times at lights, and also refused to crank afterwards for a few seconds. I did reverse it into my garage easier the day I picked it up, something may be screwy.
And my Patrol used to redline at 6000rpm actually with no problems, due to a Fireball ignition system and disabling the rev limiter