You don't need a new gun. Ions are great guns, I played with mine for CFOA all season last year, and so did the rest of the team. All your stuff is good, just get a new pack. You'll want a barrel (cp 1 piece is great and affordable) and new feedneck. The rest is up to you. Just practice against teams that are better than you, you'll find that gear really doesnt matter at all.
edit: forgot to mention ELBOW AND KNEE PADS are a must! eclipse makes the best stuff.