In large re-sealable plastic bag, combine the brown sugar, salt, pepper and cayenne. Add the pork and shake to coat. Grill the pork, covered, over indirect medium-hot heat for 20-25 minutes. Let stand for 5 minutes before slicing. Drizzle Terrapin Ridge Farms Peach Honey Mustard Dip on top, or serve on side as a dipping sauce.