Cheers guys,
I'm left a little curious however; there must be quite a difference in the heads / cams or injection system if (on the same boost level) there is over a 20hp difference between the 2wd and 4wd?

I assume the 0.48A/R isn't on the Sierras as standard then? If this is the only change, i assume the trim on the compressor is good, but the power was 'held back' with the restrictive exhaust turbine? As nitrous isn't out of the question for an easy, cheap power boost in the future for the strip, a larger exhaust housing would probably be a good point to start from...

To clarify further - will both sierra ECU's swap with both looms? Is any ECU particually better, or cheaper to modify / get more power from than another?
And are both / neither looms integral with the main sierra wiring loom - ie will the loom come with a load of redundant wires, or will it be just the Engine loom?

Cheers!
D