Complete Exhaust System has following parts.
a) Headers: Their one end is connected to the engine cylinders and other to the exhuast pipe.
b) Exhaust pipe: Connects headers to muffler
c) Muffler / Silencer: It controls the noise.
d) Catalytic Converter: Controls pollution in air
I think you are talking about Muffler / Silencer and want ur car to produce some noise
If yes, then following r the answers:
1) Noise of mufflers is almost same on all cars, depends on type of muffler. On VXR it will work fine
2) No, i don't think so. (Let experts comment on this)
3) Yes, some mufflers have that option to manually adjust/close the noise effect
4) In Saddar - Rwp, lot of auto decor shops, every-one has a variety of mufflers available.