virtually any inline six or v-6, or even opposed (Corvair-Porsche)six will sound the same with a 180 degree exhaust system. Thats when the first three cylinders of the firing order fire thru one pipe and the last three cylinders fire thru the other pipe, or in the case of a v-6 or opposed six when one whole bank fires thru one pipe and the other bank fires thru the other pipe. Once you hear it you'll recognize it.
Its easier to do on v-6s or opposed sixes since all you gotta do is just run one exhaust system (like the muffler shops do) down each side, on an inline you gotta "split" the manifold and run the dual side from the added outlet. Also on any of them you gotta keep the pipes separate--no crossover connection, no "H", or "X", or whatever alphabet soup style, or you wont get the desired sound.
Once you hear the sound you can pick out the sixes in traffic just by their exhaust note. Lots of Dodge pickups V6s get duals--if you hear the sound you quickly look for something that could be had with a six (and now-a-days its usually a pick up).
Muffler location has to do with the sharpness of the sound-long tailpipes from the muffler back is sharp; short tailpipes from the muffler back is duller sounding. (I think the longer pipe from the muffler lets the sound rattle around more before you get to hear it) Also the the muffler type itself makes quite a difference. The straight-thrus can be hard on law enforcement's ears. I've seen brand new straight thru glasspaks taken off a 283 v8 ('cause they were too quiet-factory style crossover pipe connecting the two banks) and put on a split manifold little 216 chevy and get written up on their maiden voyage (you gotta keep your foot outta it).
clear as mud?
