I don't know about SterlingStangMan but mine had the factory spoiler that needed removing. As far as the antenna, it only hits when the trunk is fully opened. Has not been an issue yet.
Looking at the quad tip section of the Corsas - you would probably need to take the faux tips out of the GT350 valance and hope the Corsa tips line up in the holes properly
I echo a lot of people here, wasn't looking for it at first, but the car I ended up with had it. Now after several months of driving with the 401a package, I couldn't imagine without.
My 12 and 13 GTs before my 2015 each had between 15-20k miles a year in commuting and travel on them. Both were manuals and not PP cars. I loved them as commuter cars and my current 15 is a daily. I say go for it
Only other one I know is Roush. I think HCM Carbon or Carbon Dynamics makes one similar to the GT350 - but they aren't exact copies and he proportions were a bit off to me.
Best of luck in your search!
So the unfortunate part about this valance is ford hardly sells it outside of just the ford racing by Borla exhaust kits. I have come across the individual valance once and it is more expensive than getting the whole exhaust kit. (One I found was about $3k just for the bumper valance) Probably...
http://www.levittownfordsupercenter.com/ford-racing-mustang-back-exhaust-system-gt350-sport-p-4653.html
Difference of 300 bucks and you get the full catback - this is where I got mine from.