I have the procomp heads on a blown (871) 545 ci fitech fuel injected monster and they work great, I am very happy with them, no issues with them, the motor makes a ton of torque, and yes I when I received them I inspected them, i cleaned them, and I installed them no extra machine work, I know your not " supposed" to do that but I wanted to prove a point about the many videos and reviews " never install these out of the box" well in my experience yes you can go out of the box, the only thing I did to them, I installed arp rocker studs, comp guide plates, and comp magnum roller rockers, after about 6 months of running with dealing a overheat issue, at the time it ran 230-235, I removed the heads inspected them, no issues heads were fine, I reinstalled them and pressure tested the cooling system and did a exhaust gas test both test passed there on there today running great and I have ran these at 9 percent under at about 12-1, and I have ran them at 19 percent overdriven at 17-1 only issue I had in both cases was tires wont stick to the ground lol need to back half now