dual exhaust on our cars is not a good idea:
A) less backpressure unless designed properly, a drop in HP too. dual would work well, however, if it was designed to deliver the right amount of backpressure.
B) more muffers/pipe will add weight to the car, one of the goals of aftermarket exhaust is to reduce weight. heavier-slower.
C) you'll have to notch the bumper for the other tip.
Now, duals have two benifits: They sound cool and they look neat. Dual is good for show cars.
What would be best is a Straight-back exhaust. Our exhaust header is cenetered, and our undercarriage open enough to allow it from the cat-back. no bends =less backpressure, but the right muffler will make it work. Perhaps a single-turbine muffler would work best. (The turbine acts like an exhaust brake, and torque would be great. Aside from a straight back exhaust, a slanted muffler-style catback setup would be good too.