I did it with only the basic upgrades you buy from the vendor (that means no proton/converter/emp/d). It's not hard, use your missiles to take out the bombers and shoot at the bombers that are not missile locked. Don't be afraid to buy stuff from the AH, it is better then the vendor gear. I wish I did have a power converter when I did it, since I bought one I just faceroll over the missions. They are so easy they need to add more bonus objectives/higher difficulties.