that's an impossible question to answer... that is totally dependent upon you... sarms are used for lean mass... you can gain some size on them and lean out tremendously but how much is dependent upon your training and diet... s4 and gw along with mk will shred some shit up if you do everything as you are supposed to...
How does mk2866 affect cardio? As I understand it GW is more effective for fat loss because it can also help you go longer/harder with cardio exercise. Though if MK could help with endurance, it wouldn't be far behind.