2057 smooths out the bottom , or 2056 smooths it out even more, both have xlnt top......all have great top but from most bottom to least it goes 2013, 2057 ,2056 and they are all xlnt pipes for the B5 it is just a preference on how you like it to feel. 2056 and 2057 have a slight mileage increase over the 2013 but not a ton .