In almost all cases, the engine will make more power when the injectors are higher up but there are some trade-offs. Additional area of wetted manifold will increase the magnitude of AFR transients upon throttle angle change.
This can be counteracted by proper accel enrichment and decel enleanment.
End-of-Injection timing parameter will have greater effect on power with the injectors further from the valve, especially with duty cycles below 50%. Any standoff created by the high mount injectors must not be allowed to condense and puddle in the air cleaner or air box assembly or the risk of fire increases dramatically.
my $.02