I always like the look of the Borla exhaust and with the version I want costing almost, if not more than $1000 USD, I think that the the Steeda's are a better choice.
But after seeing the side exhaust in person I am not sure whether I want it or not. They look weird almost as if the rear exit was designed for the mustang and the side wasn't. A GT or even a V6 with the V6 bumper 2003-2004 Mustang I saw recently and it had rear exit that looked nice. But I want a some what exotic look to my V6 and I am not sure about the exhaust.