Is there a limit on the ship modifications (eg shiel upgrade, stealth device)?

Because I wanted to use 3 stealth devices but wasn't sure if I could

Pretty sure the only limit is one modification per ship.

DingusFett said:

This is correct (well, one per ship and only as many as you have points for). Full rules can be found in the rules insert included with the Falcon and Slave I as that's where the modification cards come.

So I can have 3 shield upgrades? As long as its just that and no stealth devices and vice versa

Each ship can only have one modification. So you can not stack ship upgrade modification cards on a single ship.

RAGE1073 said:

You can have 3 shield upgrades as long as they are on 3 different ships.