My #48's flowed 170-180 and were sent to Kauffman and opened up to 230-240. If 48's flow at 230, I may as well disregard the $5000 pair of RAV tunnel ports that flowed 235 @ .600 (according to that chart)

I have flowed most every pair of Pontiac cylinder heads I have come across including a set of #37 RAI heads. All 67-71 D ports I checked flowed the same (+/- a few percent). The 37's flowed close to two pairs of #16's and 62's I have.

These were all virgin heads with stock, untouched chambers. No credence paid to seat leakage or guide wear. When I compared 4 or 5 pairs of one head number you get a mean average.

All were tested on the same bench. Maybe that bench was conservative...