The question has been asked by quite a few people before, (including me). And it's another one where you'll get a divided answer to it because of personal preference. The red car was N/A, and carbureted. It had no cats. It had all new gaskets and a good seal on the shifter boot. Four mufflers and full length, out the back tail pipes. And it stunk.
As long as you were going forward there was no problem. But any other time you could come flying up to a stop sign, and the exhaust fumes followed right along with the car,....They'd come wafting up next to a rolled down window like some sort of fume cop had just pulled me over,and ask......"Do you know how many poisonous hydrocarbons you're emitting?"
"Why no, *cough* smellofficer, I *wheeze* didn't even think I was stinking"....
"Well sir you were. I'm citing you for a smell violation,..and issuing you a warning to get an aftermarket cat installed if you don't want to smell me again"...
All I can say is even though cars existed for their majority "pre-cat" doesn't mean that they didn't stink to high hell nonetheless.
Ever followed behind a muscle car? You can smell it in your own car 4 car lengths behind dude.
Get the cats installed. There is enough evidence that you wont really affect performance, and won't negligibly hurt the overall sound of the car. MFE92 has been testifying to that since before 2011, and he competes with his car routinely.