You have to select a turbocharger according to your engine's displacement.
If you put a bigger turbocharger than what your engine can handle, you will end up with a little to no gain in overall performance and horrible engine responce. You car will also lose a considerable amount of hp and torque at low rpm (For large turbo chargers, this rpm can be roughly between 3000-4000rpm and the power loss can be much higher to a point where there's virtually no power available before the turbo kicks in) in addition to a momentary lag when you give it more gas... Imagine having to rev your engine past 3000 rpm every time when you simply want your car to get going.