I do feel porting doesn't hurt, but mainly the pump in power from head work is from the compression bump, more squish equals bigger bangs.
For my car right now all I have left do is head work. I know I'll get a substantial increase in power from it as well. A full bolt on car can only pull roughly 140whp where as one with a P&P head can pull up to 160-170 whp. Most of the gain is from the head work. Though if you looking for any serious power you need boost, there is no way around that. I don't know where all this no porting the head came talk came from unless we're talking boost? If going n/a it's really not cost effective to go that route cause in the end you would have spent just as much if not more than you would have for boost and end up with 100 less hp and way less tq.