There is a limit on noise however its not strictly on your car, its for the area's etc after certain times! built up residential estate is 112db or something I think after 7pm... not sure can find out tho!
They use it for airplanes, bikes, cars, sterios, parties etc when they really want to annoy people having fun generally!
I blasted through a tunnel the other night and got some friendly looks from a police car sitting on the other side, however I didn't get pulled and I had forgotten my front plate too haha
Best thing is to just drop the clutch and kill the revs as you go past... always drops the noise levels right off! My bike used to shake my house windows on idle, and at 15k rpm it could wake up iraq!! But man it sounded good when going past women in town