I just installed the GXP strut tower brace on my SSEi this weekend and I could really feel a difference. The car is all around tighter, over bumps it is firmer and feels better when going into hard turns. Even though they say our fire wall is the support, the fact they added one on the GXP made me think there was still room for improvement! They were right
It comes close to the master cylinder but that is the same as on the GXP. It does come very close to the alt because ours alt sticks up high and the Northstar doesn't have one in that spot but everything clears. I will get pictures in the next day or two. Looks like it is factory installed!