Pretty hard to be-itch about a set of 1000.00 heads that flow 260cfm out of the box. Are most of these cheap aftermarket heads ready out of the box? No. They need checked over, maybe the valve job corrected (that will only lead to better flow and more horsepower) like others said I bought myself a good straightedge many years ago that I check decks, valves I trust but update retainers and keepers, and in any Head I check the valve guides. A little porting work they can easily go 300, and although I never pushed a set know they can go over 320cfm. Sure better than playing with 50 year old cast iron heads.