Even though the Blacktop head includes a much more open combustion chamber (see “Head combustion- chambers”) it continue to has an increased static compression ratio (see “compression ratio”), this is purely due to the piston structure. The Silvertop piston features a incredibly tiny dome with two deeply angled exhaust flycuts, https://jdm-toyota-4a-ge16936.59bloggers.com/31768740/5-essential-elements-for-blacktop-20v-4age