A little more cash would be advisable but try this sub 5 mil build, a 4A power plant would allow better shields but will blow the budget, the turrets will hit the target when it's out of sight and allow the weapon cap to charge so that all weapons can fire when you line it up, try just 2 x class 2 pulse as the under wing hard-points have a limited firing arc even with turrets.
If you don't need the range of a 4A FSD put the surplus cash into power plant and shield, I'd stick with pulse lasers and/or m-cannons as the Cobra really doesn't have enough capacity in the power dist to run rail guns, PA's and the like, I tend to use pulse as there's no ammo requirements and they do serious hull damage for an energy weapon, it's likely that beams will cause overheat issues so use them with care (assuming you can afford them!)
http://coriolis.io/outfit/cobra_mk_...0l0403034701012h.AwRj4yKA.Aw1-kA==?bn=Cobra C