Try holding in a higher gear as you slow down approaching an intersection. If the beep never occurs then, then your belt may be too long. Stock belt is a 7PK1750. On mine, when I changed the air con compressor, the new compressor had a slightly smaller pulley. So I had to use a 7PK1740 instead. Your new alternator might have a smaller pulley too. Just check your accessory belt tension indicator on the tensioner. If the triangle points at the smaller square or is at the end where the smaller square is, then your belt is too long for the pulley combination that you have.