I installed my 20s. Any idea how much this will affect my dyno numbers?

Thanks

 

This should only change things slightly, and most likely for the lower horsepower number as your torque multiplication will be slightly less as does taller rearend gears. As for the actual number of horsepower lost, don't go chasing that number because any given day and any given dyno pull even one done shortly before or after another can yield a number within up to 5 hp above or below the actual number of hp put to the dyno. The only way to remove most of this variable is to perform the hp tests in a lab with an engine dyno.