[Krsqk]

Stealth Armor has cloaking level 2. Any sensor--Tachyon Sensors, Hyper Optics, Gravitic Sensors, Psychic Sensors, or Temporal Sensors--will detect a ship cloaked with Stealth Armor. Tachyon Sensors are available at Sensor tech levels 4-6; Hyper Optics are at Adv. Mil. Sci. TL 4-6; Grav, Psy, and Temp Sensors are racial techs. Cloaking devices provide cloaking from level 2 through level 4; sensors allow you to detect ships cloaked from level 2 (with the lowest sensors) to level 4 (with the best sensors). You don't have to research all sensor types to detect a cloaked ship; any one will do. Hyper Optics are the cheapest component and also have the cheapest research path, and are probably the best choice.