Cook pasta according to package directions, omitting salt and fat. Drain in a colander over a bowl, reserving 2/3 cup cooking liquid.
While pasta cooks, heat oil in a large skillet over medium-high heat. Remove casings from sausage. Break sausage into bite-sized pieces and add to pan; cook 3 minutes or until browned, stirring frequently to crumble. Add garlic; cook 30 seconds, stirring constantly. Add tomatoes and pepper; cover and cook 2 minutes. Mash tomatoes with the back of a wooden spoon to break them up. Cover pan; reduce heat to low, and cook 3 minutes. Remove pan from heat. Add pasta, reserved 2/3 cup cooking liquid, and arugula; toss well. Sprinkle with pecorino Romano.