I am relatively certain that the ECM in the two cars is the same................. I base this on the re-tune I had done to my Solstice ECM............... So, the "kit" to turn a Red LIne into a GT would likely have to include an ECM re-tune.
Never said you can not re-tune the computer programming, or have it reflashed, etc.
But Smog Standards in the USA & Europe are different.
Example:
When Opel made a US Legal Opel GTs, Mantas Kadetts etc. , they had to do a few things to be US Department of Transportation legal.
Some Examples:
-Opel had to add side markers for the USA market
>In Europe side markewrs are not allowed.
~Which meant sheet metal changes
-Opel had to comply with US Federal Smog requirements in 1971, which gave us the US the low power 1.9L 7.6:1 compression engines.
>In Europe they still had the high compression 9:1 1.9L engines.
~Which meant special "Dished" pistons to drop compression for the USA
-Opel had to comply with CA Smog regulations for 1975 Manta and Wagons sold, by adding a Catalytic Converter.
>Cats. in Germany were not mandated until over a decade later.
~Which meant floor board & passenger seat frame changes on the 75 Manta & Wagon to accommodate the cat.
I can add to the list, but what I want to say is "IF" GM had allowed the 2007Opel GT to come to the USA (And there was no Saturn Sky) changes would have had, to have been made to be Federally DOT Legal to sell in the USA. This would have included changes in the computer programming to be Federal Clean Air Standards & California Air Resources Board legal. "CARB"
For Example:
If a computer is reprogrammed. It must first have been issued a CARB approved number to be legally used on a public street in CA.
This comes from experience, not conjecture. I used to be CARB certified to conduct California Smog inspections. Believe me, TEST cars would be occasionally run through our shop to Test& see if the Licensed Inspector was doing his job. The penalties were & still are severe.
Remember we are talking about brand new cars, which have to be "compliant" not 40 year old Opels that in most places need go through no checks.