That dyno graph shows a nice result with that combination of parts...BUT it doesn't show the effect of the cam by itself, because they changed the cam, tuner, and mufflers at the same time. The baseline run was done with a pizz-poor AFR that was so lean it couldn't be measured. If the initial AFR had been corrected first, at least we could see how much the cam and mufflers (with updated tune) add. There's no way, with the current evidence, to tell how much bang for the buck we'd get with just the cam (or with just the ______).
Don't get me wrong, it's a very nice combination, and I don't expect many people would want to pay the price to do this the scientifically correct way...but basic science says to change only one thing at a time, and measure that effect.