Originally Posted by phelan

I can't imagine the increase to the drag coefficient from swapping exhausts to be that bad. It's not like the stock exhaust is tuned to provide laminar flow, and the maximum in aerodynamic efficiency. Every gap and bump will contribute to the drag coefficient, or in essence increase the turbulence in the area.

Yes, the low-slung cans of the FI may be even worse in terms of causing turbulent air flow. But you're better off worrying about the exterior of the car, which will have more say in the drag coefficient, than what's going on with the exhaust.

If you wanted to have a drag car that absolutely had the best aerodynamics possible, you'd put an entire underbody diffuser that guides the air in a straight flow line from front to back.