Here's the link referring to the testing that united engine and machine (kb-silvolite) has done
http://kb-silvolite.com/article.php?action=read&A_id=36The article states that the polished piston doesn't transfer heat to the intake charge as much as a non-polished one, thus the increase in performance. Here's another quote,
" A smooth polished piston runs cooler than a non-polished piston even after combustion deposits have turned both pistons black. A cool, smooth piston will transmit a minimum of heat to the incoming fuel air mix."
