Marinu Defense System this is what I use. Get 4 or 5 launchers, and fly over the ship you want to hurt badly. Release the pods when you're on top of him. If the target is too fast for you, he's probably also not too tough to take out with only primary weapons.
SAD These are awesome... when they hit their target. Too slow to take out fighter craft, and big, tough slow ships are more easily killed with the MDS.
Rocket Launcher/Turret ewwwwwww.
Hunter Missile I'd rather have a rocket launcher.
Needle Launcher kind of like a primary weapon with ammo.
Dispersal Rocket If your ship turns fast, this is more useful than the MDS.
Persuit Missile I'd use these if they could hit their target more often.
Mine Layer I have yet to try this, because I don't have enough room! It looks cool though.
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"I like ice cream without chunky bits in it... they get stuck in my tubes." Bungie's Soul