I frequently see FWD 1989-1993 Cadillacs ("C" Body) with dual exhaust tips sticking out the back, one on each side.

To the best of my knowledge, none of these cars ever had dual exhausts or dual exhaust outlets. What's up with that!!??

well, alot of poeple get dual pipes on there cars, and with the 89-93 fwd devilles you can do it sooo easy. Just get a muffler for an Fbody car and put it on. the mufflers on Fbodies are like this....
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-->|.....|

thats kinda crappy but you get the idea, one in, two out.

really? it is an easy setup?

Next year I'd like an exhaust system put on (well, aftermarket) I don't know if I should go cat-back or just muffler and tips..... I know stock piping is 2.5", I was thinking of getting a high-flow cat, but not sure if it's worth it, I was gonna get a Flow Master 40 series (I think) and run dual tips, one on each side....... didn't know if it woudl look good or not....

....should I go cat-back or not?

You said get a muffler from an F-body? what year? and there is only 1 muffler? it would be a pretty easy install? if that is all I did, would I notice any power increase? how about sound?

well you could get a high flow on from Edelbrock, should sound deeper and give you a little more power. i put a flowmaster in place of my stock and i got a little increase in seat of pants power.

well you could get a high flow on from Edelbrock, should sound deeper and give you a little more power. i put a flowmaster in place of my stock and i got a little increase in seat of pants power.

Exhaust is the most interesting of jobs for me b/c of how i did it on my blazer. I went to pepboys and bought about 150 - 250 in pipes, clamps and other stuff. Bought 2 flowmasters.

Took it all home and just started fitting parts in hanging it up. Left over stuff i returned. I plan on doing the same with the caddy in the spring

Here is little better picture (well, its 67 Eldo, so in 89-93 cars its kind of "reversed" - one pipe in and two out).
http://www.cadillac.pri.ee/EldoExhaust.jpg