Just a comment on peak HP. Peak HP is a very tiny spot on the power curve. Having just dynoed and seen countless dynos I can tell you it does not mean much.
1) The curves are full of little blips up and down. You can have identical power curves and then at the point of peak power - blip up or down 3 HP. That is a 6 HP spread, so 2 cars could have virtually identical performance and yet 1 is 6 HP stronger than another. Same is true for tourque - if you look at the curves for Duratecs for example - many cars have a nice tourque blip of say 160-165 lb/ft at about 3000 RPMs, then drop down the rest of the graph to a more typical flat 150-155 lb/ft. Really very little variation where it counts at our usable rev range 4-7K RPM.
2) Remember that usable power is area under the (usable curve). For us look at 4+K to 7K RPMs, where we spend all but the first 1-2 sec of any acceleration contest if shifting near redline. A fat curve in this range or average HP 4-6 K is what is critical. A flat peaky curve that falls off fast can have a much higher peak HP qnd still be much weaker due to area under the curves.
So, you need to see the whole graph side by side to compare. There is also probably a +/- 5 HP variation between dynos assuming the the typical Dynojet 248C dyno is used & calibrated properly. It is pretty accurate by and large though. Some variation does exist in all cars engines, but I dont believe it is as wide as peak HP numbers sugget. I think the little things account for alot - especially exhaust - little lips and flages and crushed ares in exhasut flow - manifold to catback, as well as state of the cats themselves. Remember the SVT 99 Cobra, this was a big part of a 15 HP variance. having looked at our exhaust, I think it applies here too - ie. persons with "bad stock exhausts" will benefit more from a nice smmooth Borla/Bassani than those with good exhausts. Notice how, no matter the baseline most cars are within 3-5 HP of 180 HP when all bolt ons are done.