== Radical Motorsport SR3 == 

 I'm not sure about the inclusion of the Radical Motorsport SR3 as the highest specific horsepower entry.  I did some cruising around their web site and the SR3 can only be made street legal through the Single Vehicle Approval process (the process by which a kit car, imported car, etc can be brought in by the owner and individually inspected to be declared street legal).  This doesn't really seem to count as a production car.