The standard pickups in your MIM strat are probably just regular old AlNiCo magnet mid to high output strat pickups. The CS Fat 50's are going to be lower output with a bit of a wider/warmer edge than traditional pickups. If you're not into vintage tone and are wanting hotter sound... probably not "better".
There are a lot of options for single coil setups so i would watch some videos to get an idea of the tone profile of each pickup before you buy. Or play a strat with those pickups in the store prior to buying.
