What, if anything, does your custody order say about your relocation?
When you discussed the possibility with your ex-, were you able to come to an agreement as to a long-distance visitation schedule, payment for the cost of transportation, who would accompany the children if they are younger and are to travel by plane, and the like?
Your child support payments are based upon your income, but if you take a voluntary pay cut in order to relocate you cannot count on having your support obligation reduced.

