higher compression, headers, etc.
the engine is completly different from the block up. remeber in europe premium is 98 octane or thereabouts.
instead of an engine managment system designed to keep the cat alive (us version) its got an engine managment system to create maximum volumetric efficiency.
no secondary air pump, no egr valves, no varing band o2 sensors, mixutre is constantly stoich, instead of fluxuating to keep the cat alive.
no cats obviously. its a whole nother beast.
in a nutshell
us version- keeps the tree huggers happy
euro version- keeps its balls.