The airgap was better at all rpms according to the article.
Your downplaying the difference of 16hp at the rear wheel to try to further your agenda is either disingenuous or ignorant. 16hp at the wheel is about 19 to 20 on the dyno.
That 20 hp at peak, with even bigger differences along the rpm curve is some of the easiest hp in terms of dollars spent that there is. What were you expecting with an intake swap on a less than optimal stockish 340?