if you go Zolazin (+40% Cloak), Spy (+ 20% cloak) use a Stealth Optimizer (+30% cloak for 24 hours ) and install all cloak modules in the game, you can get up to around 26K cloak on ship
that would make you more or less imposible to find for anyone not playing as Explorer (+20% scan) and running heavy scan boosts during PvP, unless you hit them first or you get alerted in theire legion
see
viewtopic.php?f=4&t=37784 for numbers on max scan, but it not 100% up to date, as dan have added a few scan modules since it was last updated
but if you are hitting enemy ships or invading planets, cloak doesnt realy help you that mutch