ZmOz is correct, but to visualize it better, picture a transverse V6 arrangement. After the exhaust leaves the front manifold, it has to be piped over the transmission, where it joins with the rear manifold, then goes "down" to the converter. Longitudinal setups, like your truck, AR, won't be configured quite the same way. In that case, after the manifold, one side comes across to meet the other, then it goes straight back into the converter. It's not really called a downpipe. On cars that have them, people replace the downpipe with pipes that are either larger (a good idea IF you're producing enough HP to need it) or one with less restrictive bends. For racing/off road only applications, there are companies that sell downpipes that'll eliminate the converter. You can get an O2 spoofing module to prevent a CEL.