[Ronbo]

You forgot to mention modding the radiator cap:

Snap off the back flow button on the bottom. Now you have a 0psi cap. Obviously, this won't work on a closed system cap.

You will need a small catch can if you don't already run one.

Another benefit is no electrolysis from dissimilar metals in your system.

The steam is more than just "theory", aircraft engines were especially susptable to flash boiling due to altitude. Alloy heads offer some advantage over iron to reduce the hot spots. There's no mystery why alloy heads allow you to run higher compression and leaner fuel ratios without detonation.

What would be interesting to see is the cylinder head temps before and after, this would be the largest impact.