[ahausheer]

I think the rules are ambiguous as to what country the part must be made available to:

ARTICLE 2.1: PURPOSE AND INTENT
2.1.1: The purpose of the Pirelli World Challenge is to provide an opportunity
for teams and manufacturers to showcase their vehicles and products
through a Championship Series of closed-circuit speed events.
2.1.2: In keeping with this purpose, vehicles and products used in the
series must be identifiable with the vehicles and products offered for sale
to the public and available through the manufacturer’s normal distribution
channels.

end

Also note that any ECU can be used, IE custom tuning. The power of these cars has nothing to do with what will be released to the public.

EDIT: An interesting note is that the headlights must be stock but can be from any country the car is sold in. So perhaps other parts can be used that are not sold in America? Just a thought.