Of course it makes a noticeable impact.
It reduces knock sensitivity, and going away from lambda 1 in either direction always reduces egt.
Im asking bc saw your post years ago, something like: lambda < 0.8 makes no sense at DI due to no vaporization effect
And this make sense
Also stock BTS with lambdasoll ~0.65 could be reason of misfires, its pretty clear with MPI setups, but didnt get the point at DI