They flow,all their heads, and have been doing it for many years... It is not what it looks like or even flows like sometimes but how,it performs on the track...
I have a 14cc head that flows great at high lift,,and a gx200 22cc head that flows poorly at high lift... Going by flow numbers the 14cc should be good, and the gx200 not so... On the track the gx200 head kicks some serious butt...
I have seen some pretty extreme port work and some not so much... But on track performance trumps all...
I have a M. Clements head big valve and if you see how he ported it compared to mine... You would think mine would flow better... And it does... But on the track the Clement head really shines...