Preheat broiler. In a large bowl combine bread crumbs, 2 tablespoons of the ketchup, 2 teaspoons of the relish, the garlic, salt, and 1/8 teaspoon of the pepper. Add ground turkey; mix well. Shape turkey mixture into four 3/4-inch-thick patties.
In a small bowl combine mayonnaise dressing, the remaining 1 tablespoon ketchup, the remaining 2 teaspoons relish, and the remaining 1/8 teaspoon pepper; set aside.
Place patties on the unheated rack of a broiler pan. Broil 4 to 5 inches from the heat for 14 to 18 minutes or until no longer pink (165 degrees F), turning once halfway through broiling.
To serve, line bottom halves of buns with lettuce leaves and tomato slices. Top with burgers and mayonnaise mixture. Replace top halves of buns.