What do you think about this statement.........

It’s the rings and the factory fuel injection that’s responsible.
I'd also add to the machining process, the machinist himself is where quality comes from, not the machine itself. I use machines from a generation before mine. I set the clearances, make the crosshatch. Not the machine, I'm sure a CNC machine would do better and faster but it still takes the dude to plug in those numbers.
I guess I'm trying to say it's takes someone wanting to do it correctly on any machine