While the Blacktop head includes a much more open combustion chamber (see “Head combustion- chambers”) it continue to has a better static compression ratio (see “compression ratio”), this is only as a result of piston layout. The Silvertop piston encompasses a really compact dome with two deeply angled exhaust flycuts, https://toyota-4a-ge82582.iyublog.com/30734395/about-4age-20v-blacktop-for-sale