[Barry_R]

Well broken in bores are rounder and better than fresh ones. When you hone a block you can accomodate for mechanical bore distortion with torque plates, you can use heated coolant and plates for thermal distortion (NASCAR & developmental testing), but you cannot readily quantify and adapt for dynamic distortion caused by 1000-2000 pounds of cylinder pressure.

The used bores and rings will do that - wearing in during operation, and putting new rings on a cleaned and prepped used bore race engine will often get a touch higher power than the engine saw the first time around. When they dyno good used engines it is not unusual for them to make more power than they did new.

Low RPM and transient throttle behavior in street engines are actually worse for a gapless strategy. The variations in ring loading make them float in the groove unsettling the sealing and bringing oil and combustion residue into the chamber. Not good for emissions.