The problem with the Cobra, despite it's hardpoints is it has very little shield capacity, and not alot of armor despite it having I [think] the fastest or second fastest speed in the game. You're better off upgrading to a larger ship than squeezing out more parts on it, to be honest.
With that said, the Cobra still has its uses, its high speed, good jump range and ample storage capacity make it perfect for smuggling.
as parry has said: the cobra has weak shields. and it has quite a big hitbox.
it is the fastest ship in the game.
you can use that speed in combat (to some extend): going into a fight fast, then moving away, till your shields are recharged (bi-weaves are great for that), using boost and FAOFF-flip boost to get behing your target etc. i would always get the best thrusters and the best powerdistributor for a cobra. i play high-res with a cobra, but i wouldn't take one into a CZ or HAZ RES (at least not for a longer time).
concerning your build: the small hardpoints are hard to hit with, i have turrets there - that helps. because a cobra won't be very long on target in combat, i'd suggest a medium beam for one of the multicannons. (or a burst as a compromise) - so that you can strip shields faster. under the belly i run turreted burst + canonn.
i think, you should have a look at either a viper mk III (if you haven't flown one) - or a diamondback scout. the scout is an amazing bountyhunter, and cheaper to outfit than a cobra. the viper mk III is even cheaper, has really good shields, but it doesn't have the jumprange or manouverability of a DBS.
