You have to factor in you are running a dual 2.5 inch exhaust. I bet the numbers you looked up would be right if you had a single 2.5 exhaust (like a honda civic or something).
No they were for dual. They list for single and dual. Google the charts and see, none of them are even close to each other which makes me think each exhaust manufacture / magazine etc. just makes up charts for marketing. There doesn't seem to be any real science or testing behind them.