Fuel Injection and Variable Timing

I was curious how much fuel injection and variable spark timing reduces fuel
consumption and increase power in an airplane engine. Auto engine data does
not help because auto engines are run over a wide range of conditions,
wereas an aviation engine typically runs at cruise power and can be
optimized for that.

So ... how much does the more modern fuel injection and electronic timing
help?

Are there any engines that come in both versions such that easy comparisions
can be made?

-Much Thanks