Someone from Titleist would need to tell you about changing the weights and they would probably need to know what shaft you have and which weight is currently installed.  I do know that you can easily lower the loft while keeping the lie angle constant by changing to the D1 setting if you are right handed or the A4 setting if you are left handed. Changing to which ever of those settings is appropriate for you will bring the loft down to 16.25 degrees, which should lower your ball flight a little.