Joined: Nov 2016
The difference in parasitic horsepower loss between incandescent bulbs and LEDS is likely going to be smaller than the % of error for any given dyno. In other words, negligible. The decision to change your headlights should be based on what you feel comfortable driving around with, light-wise, at night. IMHO, not blinding everyone while still being able to see the road is good.
I smile a lot. It makes people wonder what I'm up to...