I have a set on my shelf that went 4.86 @ 140, intake flow numbers were around 350, can't remember the exhaust. They have been ported twice, once by Muscle Motors when I bought them new and then a second time by a local Chevy guy who thought he could make them flow a little better, he's the one who gave me the flow numbers...that I have since lost. My combo was a low deck 500" striker, stock block, solid roller, injected meth in a 235" 4 link dragster. I have no complaints with them, won lots of money with them and never had one single issue. Yes, I've read all of the horror stories....