I personally would not run ant head out of the box but its nice being able to do your own work. An Edelbrock head out of the box is now a piece of CRAP!!!!!!!!! After checking out the ProMaxx heads I'm betting I could have a set ready to both on in under 2 hours time checking things over, (guides, valve job, spring pressure< ect) I didn't check every guide or spring pressures for my Friend as it was a quick, fast FREE-be. Quality and flow numbers were both better than the new set of Edelbrock heads I have sitting here for a project of mine.