I've dyno and raced motors with ported stock cast iron heads, stock Eddy RPM, CNC ported Eddy RPM, small 440 standard ports B1-BS, same B1-BS heads CNC ported to M.W., Indy SR with M.W. ports and 440-1 CNC ported. If you want more power later buy the best heads you can afford now, at least with M.W. port sizes