MIX dressing and soy sauce. Pour 1/3 cup over chicken in bowl; toss to coat. Refrigerate 1 hour to marinate. Meanwhile, mix remaining dressing mixture, peanut butter, honey and crushed red pepper.
COOK spaghetti as directed on package. Meanwhile, transfer chicken and marinade to skillet; cook and stir on medium-high heat 8 min. or until chicken is done. Place chicken in large bowl.
DRAIN spaghetti. Add to chicken mixture with peanut butter mixture and all remaining ingredients; mix lightly.