Good Morning.
Thoughts about back-pressure have been going on for a LONG time.
On a positive note a little is supposed to help scavenge the cylinders of residual exhaust gases (there's that reverse-pulse thing helping again).
Engines can go either rich or go lean with a change to a more or less wide-open exhaust system.
The lean engines were the most detrimental to themselves and without "jetting up" (richer jetting) the carburetor(s)
and/or adjusting the ignition timing, a lean mix could do some damage. (A rich fuel mixture burns quicker than a lean one).
I believe that's where the whole backpressure thing got a bad name. I remember as a kid, the old farts (like I am now) would say that you need some backpressure or you'll "Burn the engine out".
IF you decide to go with no cats, a re-tune will be required.
I have (4) Hi-Flow cats on my truck and it's a question of whether I want to put up with the "no cat smell" or maybe lose some power. I I am a self-confessed "Power Optimization Enthusiast" but when it comes to driving in peace and quiet without a smell and maybe giving up some horsepower, that wins over the alternative (for me), hands down.
(4) cats might be costing me 20 horsepower (I doubt it), but I don't really care.
My engine freely buzzes to it's shift point (currently 6450), produces somewhere close to 800 flywheel and gets decent gas mileage. Good enough for me.
Muffler and Hi-Flow cat tech has come a long way. Back in the day, open headers were so common at racetracks. Today- Even with the 4000+ horsepower rigs, they aren't running open headers. It is rare to see/hear that now.
The factories have been getting on the cutouts (more noise) bandwagon lately. Even my daughter's stock new AMG can make more noise than I personally like.
In the end, your personal choice rules.
Have fun.