I think you may need to re read the article, the stock bike made 50 hp, the pipe didnt add any hp to this peak, however it allowed it to make 7 hp more
MXA page 66 says in stock trim the KTM peaks at 50hp @ 8400rpm.
Pro Circuit pipe adds 1/2 hp @ 8500rpm and 5 1/4 @ 9000rpm and "an amazing 7 horses more at 9500rpm" ( I think they meant a total of 7hp).
The Pro Circuit pipe makes more power even though the rpms are higher but in stock trim it only makes 50hp peak as in no more power at any rpm. The article also stated that just adding the Pro Circuit silencer would give you 2 more horse from 8600rpm to 10,000rpm. I interpret that to mean it makes more power not just moving the powerband around?
Not sure I understand your response?
I would provide links for both MXA articles but they seem to be magazine only as I could not find them online at MXA.