Cook rotini according to package directions; drain and refrigerate. In large skillet over medium heat, sauté SPAM® until lightly browned; cool. In large bowl, combine rotini, SPAM®, beans, corn, cheese, bell pepper, onion, tomato and olives. In small bowl, combine CHI-CHI'S® Salsa, sour cream and mayonnaise. Toss together salsa mixture and SPAM™ mixture. Cover and refrigerate several hours. Spoon salad mixture over lettuce. Serve with CHI-CHI'S® Tortilla Chips.