Back pressure applyies to old V8's. The most important thing in new small engine cars is the pulse rate of the exhaust. Thats why for the 2.0 zetec 2.25 exhaust is the best option instead of 3" however the dual set up messe the pulse rate a little. It will gain but not as much as a single outlet. That is why you dont see many 3" dulas on these cars or anyother SCC for that matter unless they are running turbos and still on the zetec unless your over 300 ho 2.5 is sitll better for a turbo setup.
