1. For sauce, in a bowl, combine whiskey, honey lager mustard, and peach and bourbon sauce. Mix well and set aside.
2. Preheat grill to medium- 350 to 450 degree F.
3. Place brats on grill and cook according to package direction.
4. Using a knife make ½-inch deep slits crosswise, about ½-inch apart on top of each brats.
5. Place them on the upper rack of grill. Close the lid and cook for 2-3 minutes.
6. Baste brats generously with sauce. Cover and cook for 1-2 minutes.
7. Serve hot with toasted buns and topping of your choice.