The engine is running better due to runin (or as we say break in). Saitos seem to run better with age and more hours on them provided they have been properly lubricated. Fuel consumption will go up with a Perry Pump or Cline system as it is being force fed to the carb (albeit at a constant rate). That is why the engine does not tend to go lean at the end of the flight with those systems installed. Those systems are very consistent in operation, less variance and thus slight increase in fuel consumption. I found the Perry Pump made my airplane run a little rich. When I took it off, I leaned out the engine. I really did not need a Perry Pump in my application, it was sort of a trail run to see how it operated. While it ran well, the engine seemed to run better without the Perry Pump, at least it used less fuel.

Cheers,

Chip