[Suicide Junkie]

As a note:

ECM does not cloak your ship, it just makes it harder to hit in combat.

A Class 1 sensor, has a detection ability of 2.
A Class 1 cloak, has a Cloak ability of 2.
Stealth armor, has a cloak ability of 2.
In the end-game, max sensors beat max cloak.

Thus, a sensor of class X, can beat any cloak of class X or lower, and any sensor can defeat stealth armor.