Chain guard is bolted to the swingarm, and the stock one is plastic.So you have an alloy front sprocket cover ? It is a small piece and is supported in several places and bolted securely to the transmission case in several spots. An alloy chain guard would be just hanging out there exposed and not very well supported. It woul be prone to damage. At any rate, I’ve never seen one. I f you know what brand your sprocket cover is, contact them.