What is difference whether the silencer has got one or two exhaust pipes?

Question

My 1999 Opel Vectra B has got one exhaust pipe at the silencer.

Now I have to exchange it and see models with one either two exhaust pipes.

What's the difference?

Answer 1

Usually very little if the two pipes are on the same silencer box.

If, however, there are two rear boxes, one on each side then the system tends to be less restrictive.

Two pipes are usually for a "sport" badge... etc along with the "go faster" stripes...

A larger single can be very close in effective diameter to two singles depending on the sizes.