Yes, Vikki, you're right, you can only compare heads that have been flowed on the same flow bench. I compensate for weather conditions and calibrate my flow bench to make sure that I get consistent numbers over the years but I don't use other people's numbers directly against my tests. That's why I usually make a note of the percentage difference from stock rather than quoting the numbers.

The numbers that I have for a set of stock 48s show around 230 cfm at .500" lift, the Edelbrocks 285 cfm at .500" lift. That's about 25% better and that translates to about 50 hp on the dyno depending on the combo.