Thanks for posting that. You've just help prove the power of the K&N. According to Shiv the ignition advance multiplier goes to its lowest setting after an ECU reset which would mean any gains right after an ECU reset would be caused due to an aftermarket part being installed. Once the ECU detects any knock at all it begins decreasing the multiplier.
What this means: the 12 hp gain after resetting is all intake. If the power was causing it to run lean or detonate the ECU would pull timing and that 12 hp gain would not be reproducable but it was which means that 12hp gain is safely achieved.