I'm not sure that ANY of that is generally true.
It likely SOUNDS like it has more power.
Changing the air flow usually results in a leaner mixture and most engines these days are lean to start with.
And the pipes might run cooler but not the engine overall.
And it is illegal to modify exhaust systems in the US; might not cause you a problem......but still illegal.
In it's stock form, the Spyder will easily exceed any speed limit in existence so unless you are going to race it on a track, what's the point of having a few extra HP anyway ??