I did a search for the purpose of the resonator in exhaust systems and one result took me to an old thread on here where a guy was looking for correct dual exhaust for his car. Most of you probably already know about this but I found a PDF for Oldsmobile parts and accessories and thought I'd share it. It looks pretty invaluable to me. Maybe another newbie like me will find it useful.

http://www.usapartssupply.com/upload...75_catalog.pdf