Greg Good

Big E, that flow sheet looks typical of a head that flows well up through the curve, but gets turbulent up at high lift. 341 is certainly attainable, and if the shop has a good reputation I'd try them. I would like to have seen what the intake port flow was at .650". It may have still been smooth there. I don't think the 341 was inserted there as you have been told. As a matter of fact it would be my bet that they are being honest by showing that the head got turbulent and backed up after .600" lift. It's real common for a factory LS head to go turbulent past .600" lift. You can smooth them out, but you get dangerously close to water doing it.

Just my two cents.