A turbo charger will take alot of the noise from the exhaust sound. Act something like a muffler. So a vehicle fitted with a turbo can have an exhaust that would be too loud for most people *if* that exhaust was used on a non-turbo application.
Now, lots of muffler makers just label "turbo" on a product because it sounds like a cool thing for those that don't know better.
A high flow performance muffler would be fine, but a *real turbo* muffler would get the cops attention. Unless you have a turbo-X.

dave and xtoy - and that's not likely