The photo below should be self explanatory and should provide the information needed to install a Camaro muffler on a Reatta.
I suggest that anyone wanting to install the Camaro muffler on a Reatta look at the muffler before installing. Look into the single end (that will be used as the inlet) and make sure it is not straight thru. If it is, it will be too loud for most Reatta owners.
I have a couple of exhaust catalogs and they say you can use any of the ports as inlets or outlets. I'm not sure ALL mufflers are made that way.
Thanks to Barney Eaton, member of the Reatta forums, for this information.
