ok folks dual exhaust lesson 1:
the dual exhaust was originaly produced to be put on early american muscle cars. The design was also used for V8's in the british racing series. This was because a V8 is basicly two inline 4's like we have. A v8 requires two headers one on the left of the engine and one on the right. which means that they need piping from the right header to the back of the car. and from the left header to the back of the car. Instead of combing them and creating more pressure in the single exhaust, hinderin performance, some dude was like s**t! lets jsut make it easier and faster and better by having two!
Since we only have one header, a second pipe is just a waste of money, time, weight, and respect.