Unless you have the knowledge and equipment to tune the position of the vortex generator very precisely, the vortex generators will only help if you get extremely lucky with position. The EVO VGs were very precisely tuned. We can't really hope to duplicate that in our garages. That's something like a consensus on VGs among the most engaged and experienced folks on this forum, from what I have seen.
Also a consensus, a kamm is better than a wing, and a boat tail is better than a kamm. I partial kamm off the top of the window and a flat trunk lid spoiler might be a good combination. An airdam, grill blocking, and wheel skirts are also typical recommendations. They seem to work very well in most scenarios.
