"Q. Can I have duals and have the pipes ran out the back where the factory pipes were?
A. Yes. It can be done but it usually is a bit expensive to get the pipes ran out the back. This is due to it being fairly difficult to get both pipes over the axle because it is very space limited up there. There are setups that have both pipes going over the passenger side on the rear axle and there are setups that have one pipe over the driver axle and the other pipe goes under the axle. Also, you can buy a new upper PHR to help running 2 pipes over the passenger side of the rear end (see post#2)."
http://www.ls1tech.com/forums/showthread.php?t=531756 few pages of different setups on that topic
deadtread please tell me that wasnt always your slogan under your name...f'in hilarious