Place the sausage in a frying pan, add 1/4 cup water, cover and cook over medium-high heat 6 minutes. Remove the lid and cook for an additional 15 minutes, until the water evaporates and the sausage is browned. Pour off any excess fat.
Bring 6 quarts of water to a boil and add 2 tablespoons salt. Cook the ziti in the boiling water according to the package directions, until tender yet al dente.
Meanwhile, add the ricotta to the sausages and mix in the pepper flakes and salt and pepper, to taste. Drain the cooked pasta, reserving the cooking liquid, and stir it in to the sausage/ricotta mixture.
Add some of the pasta cooking water if necessary to loosen up the mixture, and season again with salt and pepper, if necessary. Top with grated pecorino and divide evenly among 6 pasta bowls.