1. Preheat grill.
  2. In a small saucepan combine syrup, bourbon, butter and vinegar. Boil over medium-high heat until thickened, about 3 minutes.
  3. Season salmon with salt and pepper.
  4. Grill fillets about 3 minutes, then flip. Baste with maple glaze and grill for 2-3 minutes more. Baste again before serving.