Afr 260cc 100% cnc ported ls3 aluminum cylinder heads 6 bolt mongoose. 650 lift we do not lower invoice values since it is a violation of us and international custom laws. 260cc Street Head Flow Chart. Note Milling head deck will affect flow numbers. CNC Porting Occasionally a 100% CNC ported head might have a very small area left as cast, this in no way affects performance.