MIX dressing mix, oil, lime juice, cilantro and chili powder until well blended. Pour 1/2 cup of the dressing mixture over chicken in resealable plastic bag; seal bag. Refrigerate 1 hour to marinate. Mix remaining dressing mixture, mangos, red peppers and onions in medium bowl; cover. Refrigerate until ready to use.
PREHEAT grill to medium-high heat. Remove chicken from marinade; discard marinade. Grill chicken 6 to 8 minutes on each side or until cooked through.
SERVE with mango mixture.