Just to reinforce what others are saying. My small block Eddies flowed 217 stock on the intake with a 4.03 bore plate. Not 255cfm that Eddy says. I called the tech line and their response is that their numbers are accurate to 10% and that they use a 4.125 bore. That means they take the real number and inflate it 10%. I was really disappointed with the outcome. My J heads flow 255 and to put the eddys on would probably go slower.