porting heads

I used to gasket match the top and sides - I no longer do that. Shape the bowl and smooth the transitions but I do not enlarge the port exit in any way anymore. Your heads are already realy good, and if you think the shape of that port really matters, you're overlooking the basic physics of a cylinder full of very high pressure gases that suddenly opens an escape route. It's much more important that the port be an extension of the header primary and not a larger volume leading to it.