This is only a turbo change but not direct comparison as i now remember they were at different boost levels with different fuels used but you can see that with NOTHING CHANGED they are laggier.
Now the engine was designed and built with HKS 2530's in mind, so the GT-RS's were not able to stretch their legs or come on harder earlier...a GT-RS engine has to be done completely different (you build an engine similar to that if you were running a big single..massive cams porting etc)
also anyone who says they need a larger capacity to be fully effective is just guessing, and not speaking from experience.