We dropped down to fourth gear (1.25:1) for the next three pulls, which lasted about 15 seconds each (an extensive cool-down period of five to 10 minutes between runs lowered engine and transmission temps to around 180 degrees F). These results were closely clustered:
430.6 hp @ 6700 rpm & 425.3 lb-ft @ 3900 rpm
425.8 hp @ 6000 rpm & 433.1 lb-ft @ 3800 rpm
435.8 hp @ 6800 rpm & 439.1 lb-ft @ 3900 rpm
K&N's policy is to select the median of three consistent runs, which was the first of our fourth-gear runs.
That brings our hyper-conservative estimate in at:
507 hp at 6800 rpm and 500 pound-feet at 3200 rpm
Weird, they showed lower power in 5th gear. Not sure why.