It's not SO much size. Or even compression ratio. It's more what happens because of it. If cutting the heads will give you better quench. And will increase the performance of the combustion chamber because of it. It will run that much better. You might only see a few horsepower. Maybe "not worth it" to some folks. But you will see a great increase in throttle response. Crispness. And general performance.
Think of some of the engines you hear. How they REALLY crackle when they idle. Really hard sharp pops from the combustion chambers. That comes partly from how "hard" the combustion is. Obviously compression ratio raises this. But so does quench and combustion chamber size. The better the "squeeze" the better the result. And it can set two nearly identical engines apart from each other.
