Surely the prime poiint of a 'sports' exhaust is to improve gasflow and therefore make the car peform better? If it's just a 'louder' exhaust you want, then there are cheaper options than a full sports system.
As I understand it a faster flow e.g. a 200 cell cat means the Turbo spins up faster as the exhaust gas velocity is higher. I can't see why a sports exhaust by removing baffles etc doesn't increase the velocity and therefore the turbo pick up
