318 head porting for the average joe

I was reading the OP and Shady Dell's site the stock heads flowed 175 cfm untouched but everything I've read so far say they flow 135 cfm stock which I always thought was low even with small port and valves. I'm guessing the low number is from a old test done at a lower "inches of water" or some Old Wives Tale that keeps getting passed on. So if a 318 flows 175 cfm than there not the dog head everyone makes them out to be.