Turbo mufflers are really designed for a turbo vehicle, that's why
they are very free flowing and don't do much to change the sound.
A turbocharger tends to quiet the exhaust tone a fair bit, and also
supplies the back pressure the engine needs to run right, that's why
a turbo exhaust system is usually larger than what would be needed
for a non turbo engine.
All this being said,I had a turbo muff before the turbo was installed
and it was too loud on the freeway, and caused that droning that
hurts the ears at certain RPMs, in fact my turbo engine sound with
a cat and no muff was quieter that no turbo and a turbo muff
Choose wisely, I now use a quiet muff and find it has plenty of sound
Wild