Regardless that the Blacktop head incorporates a much more open up combustion chamber (see “Head combustion- chambers”) it however has a better static compression ratio (see “compression ratio”), this is only because of the piston design. The Silvertop piston incorporates a really compact dome with two deeply angled exhaust flycuts, https://kylerizcxl.glifeblog.com/30565096/an-unbiased-view-of-4age-20v-itbs