PLACE ribs on large sheet heavy-duty foil. Mix sugar and bourbon; spread over ribs. Wrap ribs in foil. Refrigerate 1 hour.
HEAT charcoal grill to medium heat. Arrange coals evenly on each side of charcoal grate. Place wrapped ribs in center of grate; cover with lid. Grill ribs 2 hours.
REMOVE ribs from foil; discard foil. Place ribs, meat-sides down, on grill. Brush with 1/4 cup barbecue sauce. Grill 10 min., turning after 5 min. and brushing with remaining barbecue sauce.