If your going from a 6.08 to a 6.03, you will definitely notice a difference in accuracy. More specifically, your groupings will become tighter. You'll probably see a bit more as far as range goes as well.
When you do install it, check to make sure you aren't firing too hot as the added pressure of a tightbore barrel will increase the air pressure bringing your fps up a bit.
Good luck friend and welcome to airsoft!