Combine maple syrup, brown sugar, mustard, salt and cayenne in a non-stick skillet over medium-high heat. Add Lit'l Smokies smoked sausages and bring to a simmer. Heat, stirring occasionally, until sauce is reduced and almost gone, about 15 minutes. Sauce will be thick.
Remove smoked sausages on to a parchment-lined baking sheet and when cool enough to handle, dip in pistachios. Serve warm.