Preheat your Yoder Smokers YS640 pellet grill to 225ºF.
Trim the fat cap and silver skin from the surface of the pork loin. Blanch your garlic in almost simmering water for 1-2 minutes to slightly soften. Working in a grid pattern, insert a paring knife from the top of the roast, straight down, stopping when you get to the center of the roast. Insert a clove (or half clove, if large) of garlic in the pocket. Do this every few inches.
Smoke the loin on the second shelf of the cooker for about three hours. Turn the cooker up to 400ºF, brush on a thicker layer of the House of Q Slow Smoke Gold Mustard Sauce. Continue cooking until the internal temperature reaches 140ºF. Remove from the cooker. Tent with foil and rest 20-30 minutes before slicing to serve.