It is definitely on the list, but at this point in time I think I'll be postponing it. I need to first address the sides of the car; I'm thinking OEM ST side skirts (~$600!) or side diffusers, as my Grand Prix has. The rear valence would look too 'heavy' compared to just stock side skirts.
I have spent a lot of time over the past couple of days looking for retailers and firing off emails regarding some Roush Mustang side diffusers. No promising leads yet. I'm hoping to find a set within Canada.
2012 YB ST-Converted Focus Sedan [Performance Ford, Sept '14]
1992 BW Grand Prix SE Sedan [restomod project]