HEAT grill to medium-high heat.
MICROWAVE potatoes and water in 2-qt. covered microwaveable dish on HIGH 8 min.; drain. Add garlic and 2 Tbsp. dressing; toss to coat. Spoon onto large sheet of heavy-duty foil sprayed with cooking spray; fold to make packet.
GRILL 20 min. or until potatoes are tender, turning packet after 10 min.
MIX mayo and remaining dressing in large bowl until blended. Add potatoes, peppers and bacon; mix lightly. Serve warm.