The G8 has a single piece "waterfall design" centre stack which extends from windscreen height to gear shift surround height.
The G8 centre stack meets the gear shift surround at a sharp angle.
If you want to fit an Omega GPS pod, Calais Airvent pod, HSV triple gauge pod or Performance Defined 5 gauge pod then all of these are designed to fit with a "horizontal design" centre stack.
All of the "horizontal design" items use a Calais stereo stack surround trim which is only 2/3 height (it only reaches as high as the horizontal dash strip), and it meets the gear shift surround with a radiused curve.