Preheat oven to 350 degrees. Cook the macaroni according to the package directions; drain and return to the pot. Stir in contents of the cheese packets and sour cream. Transfer the macaroni mixture into a greased 9 x 13 baking dish.
In a small bowl combine tomatoes and the pizza sauce. Spread over the top of the macaroni. Top with both the green and red bell peppers, cheese then the pepperoni.