Originally Posted by jmackinjersey
I'd like to get an entire true dual exhaust starting with some true headers, going into 2.5" tubes to twin muflers out the center where the stock mufler is now. That would greatly improve the performance. I don't understand why they did the exhaust the way they did. This would let the car breath a heck of a lot better and free up some HP.
A setup like you've described here would free up a bit of top-end power, but you'd sacrifice a little bit on the bottom end. You want some back pressure on a normally aspirated car to help create a resonant pulse within the exhaust. This pulse aides the scavenging effect and really helps to pull the exhaust from the engine. This back pressure isn't as necessary in the upper revs, though.
One thing to note is that you should try to work in the direction of the engine. A free flowing exhaust is useless if the engine isn't taking in any more air to compensate. I haven't seen any kind of flow testing for the Crossfire intake, but I'd imagine you could free it up some (whether it be with simple K&N's or some other, more elaborate, intake system). From there you can go to work on the exhaust.