Piston Crowns And Combustion Chambers.
Flat-top pistons, and compact combustion chambers are a the choice of Worldclass engine builders, they will always will reduce the quench area clearance and the cylinder head chamber volumes before installing raised domed pistons.
Although it seems the easiest way towards increasing an engine’s compression ratio, a raised-domed piston is not the best choice. A raised domed piston's intrusion into the combustion chamber, will reduce an engines ability to make HP and Torque. Unless you have unlimited capital to invest in dyno time to develop a piston crown that works, you should limit the height of the piston’s crown to about 0.100” of an inch.
A way to measure how effectively a combustion chamber is burning the air / fuel mixture charge is in the amount of ignition advance needed to make maximum HP and Torque. Any pressure rise on the compression side of the piston’s stroke due to ignition advance is negative power. The only reason the plug is fired before TDC is to compensate for ignition delay.