I spent a lot of time thinking about this as a love the look a the back.
However there is a few stumbling blocks. First there isnt room at the back with the fuel tank to run another muffler. So that means either chopping out the spare wheel well and running a fuel cell to make room or fitting some other small tank. Then the other problem is that a I6 will not sound too good through dual exhausts.
I decided against it in the end. Too much time money and effort for an average sounding exhaust system that looks fantastic
Check out my research / ramblings here http://www.viczcar.com/forum/index.php/topic,5977.0.html