Most of the farm pullers turn up the pump to add more fuel/power.
But they also will add different turbos, lines, injectors, or even just having a turbo makes a difference. As stated before, you can add all the fuel you want, but without the extra air it's not gonna do anything. Adding a turbo will give more air to help with combustion and less fuel waste. Guys have added turbos to the little cubs and I'm sure have turned up the fuel. I've gotta couple diesel cubs, but am leary to mess with anything on the pump. They run just fine how they are.
