One thing that bothers me about that Artical is it makes it sound like you can't improve on stock.........and that's not true. If you don't know what you're doing then Yeah leave it stock. I'm 21 and have been working on Hondas since I was 10. My dad has been working on them since the 70's and when he was my age was head of a pit crew for a Funny Car, and I learned everything from him. People like me with the background and knowlage that I've obtained can improve. I don't mean to sound full of myself though. I sit for sometimes months planing my next Major Mod. The most recent one I've been planing for over a year. Meanwhile some tool kid with a DC5 is pissed at me casue the intake and header I put on isn't making him hit 10's. Most of these kid don't understand the blood and sweat that goes into these cars that actually produce power.
Sorry though.....I had to get that out.
I don't think the article was saying you can't improve stock at all. Certainly you can. Usually you improve on stock but you add noise, or environmental polution, or both.
My Focus was a PZEV model and the intake was designed to be unserviced for 100k miles, and let out no evaporative emissions, which means it was very very restrictive and contributed to pumping losses. An aftermarket filter on that car added 10hp, which is unheard of from an intake.
Sure if you strip out cats and such you gain power as well as long as you retain enough back preasure.
Anyway... I still think it's your cam that is causing the problem. I wouldn't mess a whole lot with cams without actual tuning... I don't know a lot about Hondas but on the Focus you could adjust the stock cam and gain a bit of peak HP but you would lose elsewhere and for sure if you were going to install aftermarket you would need a tuner shop to help you out.