They will always be able to get more power out of the same displacement, given enough time to develop the technology. Variable valve timing is an example of this. I don't even think it should be the focus in new models, although it's very nice to have a little more grunt. I don't mind 100 hp per liter going to only 105 per liter in a model change (400 to 420 hp for 4 liters) if it is accompanied by less weight and suspension upgrades. In a GT class car, you don't need much more than 450 hp if you have the handling and light weight. Imagine how quick the GT3 would be if it weighed 2500 pounds. 11 second quarter miles anyone? If you want more power go to GTS.