The marauder is already well known for its stock loadout, and its good.... BUT!.. I'm not kidding I've done full heavy runs with my semi-trained tactician in a Marauder with this setup on it. 80% of the time she'll get a headshot and save any heavy or heavier mech for full salvage. This is now my moneymaker. if you wish to upgrade it later, i recommend a gauss & two large lasers and a master tactician.. you know now how it is to be uncle scrooge mcduck!. Tip: Remove the arm mod, and two SL for more armor / HS. Switch out the 2 AC for a gauss rifle, or LBX 10 AC.
If you are looking for a reliable head shooter: Marauder 3D, large pulse laser ++, 2 large laser +++, 2 med laser +++, nearly max front armor, and some extra equipment (TTS?) to make your aiming even better. Some double heat sinks. With a maxed out pilot in tactics and weapons you can get a chance of 35% for head shots. Killed legions of assaults for me. https://www.bilderhoster.net/wrpghvxl.png.html