Same here. As for installation its way easy! Remove your stator cover, unbend the washer on the nut on the sprocket, take the nut off, slide the old sprocket off, put the washer back on, put the new sprocket on, bend the washer over the nut, put the stator cover back on. and the funnest part- adjust your chain to accomadate your new sprocket! And yes, you can use the stock chain if you are putting on a 13 tooth.