I have had mine on two different cars for at least 10+ years and they sit outside all year long.

I have headers 3" to the x pipe and 2.5 back including the long case super turbo mufflers in offset in/out (gm locations) on the 496 in my Polara.With the x pipe sound is not loud at all.Mine did get quiter when I switched to the flowcrapper mandrel bent tailpipes with turn downs at the bumper.

IIRC the Super Turbo mufflers are reversible so you can get the configuration you need and turn it backwards.

I had the Borla pro xs on my supercharger mustang and loved it but I did have an X pipe and tailpipes.