Cook the elbow macaroni according to package instructions. Drain and rinse under cold water to cool.
In a large mixing bowl, combine the mayonnaise, sour cream, lime juice, chili powder, garlic powder, onion powder, salt, and black pepper. Mix until smooth.
Add the cooled macaroni, corn, diced red bell pepper, and chopped cilantro to the bowl. Stir until everything is well coated with the dressing.
If using, gently fold in the crumbled feta cheese.
Cover the salad and refrigerate for at least 30 minutes to allow the flavors to meld.
Serve chilled or at room temperature.