Those seem to be a very good option.I have kooks long tube headers with a off rd x pipe (no cats) with roush mufflers it was way too loud but I added two flo-pro twisters in just before my rear end. Car has no drone period can’t even hear the car cruising around 75/80 mph but once u down shift a few gears and it’s hammer time it’s still loud.
Part of the S197 sound issues are the rear mounted mufflers.
I run the complete 3” SW kit and it includes resonators under the cabin but these would probably be a better option, and catch less E85 condensation than the SW retro chambered mufflers (resonators).
-J