While ported NPIs can flow decent numbers, they still don't make the same power. I'm not knowledgeable enough to say if it's the lack of velocity, or flow numbers at lower lift, or poor port shape design, but how many REALLY fast NPIs have you ever seen? I've seen one, the one I mentioned earlier in this thread. And it was only 11.90s NA, and mid 10s FI; that car was pretty much a max effort car, too (fully ported heads, stage 3 cams, Edlebrock intake, E85, 7500 rpm, etc.). PI head cars have gone 10s NA, and will run close to mid 10s FI on stock heads AND cams.
My old setup was NPI heads, blower cams, and the blower at about 7 pounds of boost. It trapped a best of 112 mph. After a piston decided to take a crap, my entire setup was swapped over to a PI motor. Same blower, same cams, same everything. It trapped over 118 on several occasions. A 6 mph difference. My point: I agree that the stock NPI intake and stock NPI cams are big restrictions, but the fact remains that the NPI heads don't make the same power as the PI heads. Period.