The 1/4 mile trap was exactly inline with my own test at Sacto dragstrip. I'm going to retry our MP4-vs-458 drag race in a couple of months, this time using tire warmers to get the rears up to 160F so both cars will have some grip off the line. We'll see how much the extra 25HP adds to the trap speed.
And Mark - not sure if you're kidding about the power seats? I've never seen a weight figure for them, but even "heavy" MBZ seats are <100 lbs for the pair, and I don't expect the McLaren power seats are >35 lbs each, so the difference between power and non-power seats would be undetectable in a 3300lb curb weight vehicle.