Rezen6.5,
Shorter string on your bow will be like twisting up your original string on the bow, therefore,
1) It increases your brace height, which generally, a higher brace height = a quieter shooting bow and should give decent arrow flight.
2) But, too high of a brace height tends to make the bow pull harder because you're stressing the limbs more.
3) On the other hand, a lower brace height (let's assume with your longer string), will make the bow pull easier and provide more arrow speed (because your power stroke is longer). Although, too low of a brace height could cause bad arrow flight, make the bow noisy and cause recoil/vibration.
Here's where you need to experiment with different brace heights to determine what best works for you and you equipment.