I think way too much is made of "Siamese" ports as it was of the original twins! Those guys got married to two different women and raised families. There must have been some strange times but function ruled! It's not like any adjoining ports are firing in secession or even on the same revolution. Much has been said about the ports acting as a plenum. That could be a + in a turbo/supercharge application. In a NA engine it seems that port shape and size would make more difference than how often a port was called on to perform. Yes 12 port cross flow with perfect ports, valves, rockers, and chambers would be nice, but in reality just how much better is it?
