The suppressors can be replaced with tyrant or small suppressors for critical chance but because smgs already come with increased critical chance I went for crit damage to increase self preserved healing. The loud vents also increase threat which is what I was going for. The sidearm required more crit chance so gave it the tyrant suppressor. Plenty of things can be changed for preference. Defib with dmg reduction after reviving an ally can work too if your teammates die, but with enough threat and survivability you should be able to take the heat for them. EDIT: The healing signiture link may provide more survivability because the damage reduction cap and the precision talent will greatly increase your weapon crit healing. Also rate of fire, magazine capacity and lastly reload speed are great stats to roll on your weapon attachments besides the main crit chance and crit damage you need. Check out my two improved tank builds that prove to be more efficient. Cover to cover damage reduction is most useful on legendary difficulty. The pulse and damage shield have the most width and coverage so I would choose one of those, preferably the pulsing shield, but the other one is taller.