297@wheels maybe his dyno was just giving out the numbers people expect, was it a DD by any chance ?.
I've personally seen dark greens(803) at 80% duty by 310bhp(crank).
When I had a chip done and set up by the person who did the last chip I was getting around 240 a tank taking it very easy, had good torque but used to foul plugs when in town, I don't usually go over 1500rpm for hour upon hour.
I tested the chip on my local RR and it was 10.3 AFR on a steady state 30mph in 3rd gear, just went off the scale rich when booted.
Best thing I ever did was ditch the L6 and the strangle hold it had as I had to use certain people parts etc for any upgrades.
I got a new ecu, mapped to absoloute perfection starts idles perfect hot or cold, can't feel it idling at all, runs down to 900rpm in top gear and pulls no snatch, and I can do 400 to a tank without trying really hard, just like normal everyday traffic speed driving.
AFR's I have no idea about and not bothered, the off boost power is untrue, boost from 1400rpm, full boost by 2500rpm.
Freedom from the L6 cost me about £1k all in, inc mapping costs, best thing I ever did, but if not wanting to do this, get it LIVE mapped, well worth the money.
tabetha