It may also have to do with what gear the Dyno pull ocurred in. Does the CS car have different gear ratios? When you do a dyno pull the gear that is as close to 1:1 is going to give you the best "real world" results. I can only speak from my experience with tuning on other MR2s but math is math and physics is physics. The same priciples apply to all. Most of the pulls we do are in 3rd and then 4th gear. The 4th gear pulls always show a lower HP reading.
"Every car I've ever dyno tested in both 3rd and 4th has made more RWHP in 3rd, with worse spool characteristics. It's basic physics. The dyno is measuring how fast you are accelerating a mass with known inertia. (the roller) Your car is obviously going to accelerate the roller faster in third gear than it does in 4th. The reason the spool is worse in third is because there is less load on the engine, and less time for the turbo to fully spool. If your car made more hp in 4th, my money says you had some other variable between the runs, other than what gear the car was in. (whether were aware of that variable is another thing)"- KO Racing
Now we all know the 360 doesn't have a turbo but the same basic physics apply the HP variation just won't be as dramatic as that of a turbo car. If the CS has a slightly dif ratio in any of the gears and they weren't aware of it, to make adjustments to the calculations, they probably ran it with the same ratios in the computer.
So, does teh CS have diff ratios? Gears 1-6 or differential ratio?