Sounds like you have jib slot issues.
A full main will close the slot and so will a leech line in the jib. The new jib will have a harder leech anyhow [which is a good thing] but there should be no need for any tension in the leech or foot lines, these are generally used to prolong the life of a dieing sail.
do you have leech telltails on the main - very important to get the main leech tension right which is vital to pointing.