the 2.0 blacktop head has what looks to be the same size bowls as the silvertop 2.0 head but the pistons are flat in the silvertop and dished in the blacktop, so whats going on there? are they different compression ratios or something?
cant seem to find the answer anywhere

 

Silvertop chamber is slightly larger, measured it at 48cc and measured blacktops as 40cc.

 

I wonder why they did that? So blacktop pistons in a silvertop would lower compression by how much? Would it be enough for turbo or supercharger?