Slice tenderloins lengthwise, cutting to, but not through, other side. Open halves, laying tenderloins flat. Place tenderloins in a large zip-top plastic bag. Add 1/4 cup Maple-Balsamic Dressing; seal and shake to coat. Marinate in refrigerator 20 minutes or up to 8 hours, turning bag occasionally.
Prepare grill to medium-high heat.
Place the remaining 1/4 cup Maple-Balsamic Dressing in a small saucepan, and bring to a boil. Reduce heat, and simmer 2 minutes or until syrupy.
Remove tenderloins from marinade; discard marinade. Sprinkle tenderloins evenly with salt and black pepper. Place on a grill rack coated with cooking spray; grill 8 minutes on each side or until a thermometer registers 155° or until desired degree of doneness. Remove pork from grill; cover and let stand 5 minutes. Cut pork across grain into thin slices, and drizzle with reduced Maple-Balsamic Dressing.