I have a similar setup using a Camaro tank. Exhaust exits just in front of the rear. I like it. No visible exhaust tip to have to deal with and the entire system is tucked above the bottom of the frame. I also installed the mufflers under the bed as opposed to the cab to keep noise and drone issues at bay. Here's my setup...
http://www.customclassictrucks.com/t...steel_exhaust/