are you talkin about the s1 mi2 or the s1 mission. The belt could be making the clicking noise if its clipping the cutout under neath the rear diff, but id say it would more than likely be a dud bearing with some grit in it. The diferences between an s1 mi2 and a carbon mi2 as far as i know is that the s1 has schumacher own make of carbon composite and it has an adapter to run stick packs insted of side by side packs, but there may be other differences