yes... technically they dont call it a turbo muffler just a muffler suited for turbo applications...
also less restriction the better in general BUT I believe for NA cars, the exhaust system is more critical as in, they plan for the bends, lengths etc to encourage a better scavenging effect since the pressure of the gases leaving the cylinders is not as pressurized as a turbocharged car. this is probably why when u put ur hand at the exhaust opening (when its not so hot), u can feel the gases coming out in pulses..
at least thats wat i have read so far...