How are you exactly going to monitor and test this. Pull a perfectly clean head off to look
for changes in carbon??? Dyno testing??? Or the best test of all track testing???
Various ways to monitor changes in combustion. A cheap and effective way is changes in spark plug deposits. Ideally a 5 Gas analyzer is best but an ignition scope will do too.
Even O2's will monitor changes in AFR accurately when you correspond them with spark plug reading.
You can even notice it when you have improved the burn just be the way the engine vibrates less and revs smoother.