To answer your 2 questions, in short, no you cannot bore out the engine to 3.7, it would be much cheaper to just get a 3.7 engine and drop it in along with all the ECU and other electronics you would need, and I REALLY doubt you could make a 7G tronic work without extensive electronic hacks, and even then it would be weird because the engine wouldn't be optimized for the 7 speed shift patterns. It is not worthwhile to put money into these cars to make them perform better, they should be enjoyed as they are performance wise, because no matter what you do, it will still be 4500lb SUV. If you want performance in the W163 chassis look into getting an ML55.