[rotrex]

The higher mix percentage you inject the more uniform the spray needs to be. it has litte to do with lambda.

A central injection point is not going to work well past a certain percentage and optimal lambda values for power.
The only exception are engines with dedicated wet flow manifolds from yesteryear with centrally mounted carburetors or central throttle body injection. they were DESIGNED to distribute the liquid fuel reasonably uniform across the cylinders.
A dry flow manifold does not do that.

The work around is to drown the engine in fuel from the (direct port) fuel injectors to keep everything on the rich side.
the other work around is folks using high percentages or even pure methanol.
This also covers up distribution issues as is burns well across a wide range of AFRs with excellent knock properties.
This is why IMHO often people with simple single nozzles systems make more power on meth alone that with a 50:50 mix.
WW2 and F1 in the 80is have shown that 50:50 water methanol is capable of higher power levels that methanol alone. BUT it has to be distributed uniformly across the cylinders.

You probably have seen the engine bay pictures of the WRC Subaru cars that featured Aquamist systems.
What did they use with the modern port fuel injected engines? You guess is: direct port injection with 4 nozzles pointing straight to the head's intake ports.

On a 50:50 mix you lose power once you go richer that 11.8 given you have a uniform fuel distribution. It starts to burn really slowly past that.

if you don't pay attention to distribution, you can have a single cylinder running at 15:1 and the others at some 11:1 leading your wideband sensor to read some 12:1 on average.
This can lead to piston failure.
it is the same mechanism you lose a piston if one of the fuel injectors has issues.

Big power on a large mix flow should go direct port IMHO