I've seen the question of the "new" Starfury in another forum an I remebered some stuff I read a few years back, so I did some digging. According to some articles that cite canon sources, the Aurora has ALWAYS had 4 40mm Pulse Cannons (if you look at the picture of the Aurora in the first post that is taken from the series, those blips in the upper wing roots look like guns because they are guns). Apparently, limitations in the fusion reactor prevent all four from being used at once. Apparently this limitation was solved, probably around the same time the Thunderbolt's main weapon was perfected (note: that remark linking the Tbolts weapons to the Aurora's weapons is my own conjecture and is not cited in canon sources).