A bit of curiousity

In now way am I try to say that 555bhp and nearly identical amounts of torque is not enough. In fact in a car that weighs as little as the Zonda does it is insane, and I love it. But in eveyone opinion does it seem that the AMG engine has been only moderately tuned. For example, looking at the same engine installed in the CLK GTR the engine puts out somewhere in the neighborhood of 720bhp. Why such a difference????

to keep it road-safe?
To keep it affordable?
to keep some range to play with as an owner :D

Zonda is a road-very comfortable-car....
the clk GTR is a race car with plate!
and also the anti-smog law are more restrictive in this year than in the past