Having a layer of fat helps to keep the meat nice and moist as it roasts. So we'd advise you to keep that fat cap on and we'd also advise you to score it, too. Using a sharp knife, score the fat in a crosshatch pattern--just through the fat, not into the meat. This helps the fat to render more effectively and also allows the fat to cook more crisply, making the cracklings even more crackly.