It is true that injector design has more to do with fuel injected cars, but the same principles of aerodynamics apply. He said he wanted to port and polish a D16 intake manifold. The runners are long on that manifold, and begin long before the injectors in the path of the air... where the turbulence needs to occur.

It's true that it will make less of a difference in the bowls of the valves, but if it neither helps nor hurts at that point, why pay for the polishing or spend the time doing it? If you had ever polished aluminum, you'd know what a pain in the ass it is.

I can attest to porting being beneficial on imports. I ported my GSX's head, and I'm making 433chp on pump gas... 33hp more than I'm supposed to be able to make with a big16g turbo on race gas. There has been a substantial improvement on airflow by just grinding off the rough stuff.

I swear by porting and port matching all your parts on imports because many of them have parts that don't line up as well as they were cast to. It's not so bad on Hondas because 90% of the motor is made from aluminum so it's easier to keep the tolerances correct... but companies like Toyota and Mitsubishi that have tons of different materials and the thermal expansion/contraction rates are different on those parts during the cooling process. These parts are "close enough", but never line up perfectly.

Just a word of warning... too much added diameter to the intake ports will hurt you. You will reduce the intake velocity... which has just as even more to do with atomizing fuel on a fuel injected engine as the surface texture on the intakes of "old-school" engines.