The stock pump and plungers are only capable of 20-25% more power than stock, I believe. With stock output at 120hp or so, I'd be really surprised if power is more than 150 or 160 tops. I wouldn't base power estimates on a video of an uncalibrated speedometer with no stopwatch visible, and no shot of the road ahead (downhill?)... lots of room for error there.

A performance computer of some kind (properly set up!) is preferable, or a dragstrip, or a dyno. Alternately, a GPS-checked speedo plus a stopwatch can be pretty useful on a FLAT road.