In some Ford's like the Focus, they also use a "different composition" hanger (or vane/chamber - a symposer) in just one location that tends to bring in a "rumble" into the passenger compartment due to the hanger using a different composition and a resonance chamber offset than most other hangers - which due to it's rebound effects in damping the noise (less or more depending on the frequency) changes what you hear inside the car.
So the hanger and type of hanger used can also make or break a system when it comes to the kind of noise - not just the type of noise others may hear - it's what the occupants in the car experience as the feedback to make the driver more alert and focused (sic) on the duties of travel at hand.
So if you have a large pipe I.D. greater than the stock - the tone lowers - but remember too - the amount of air that is needed to fully resound (develop that low rumble into an effective sound) requires a considerable amount of air in the puff out of the cylinder per stroke - the Fiesta isn't capable of pulsing enough into a tube to make it's into such a beast - instead it makes a noisy racket that sounds similar to a tin horn - the drone lacks depth and resonance.