It depends on what the label states. If it states something like; "Contains up to 5% water, salt, sodium phosphate....", that phrase may also begin with "All Natural" if just salt, and not the sodium phosphate is listed. With these type of turkeys you will get no or little benefit from brining; unless you do a brining method Pachanga uses Brine Pachanga
; but the time frame doesn't allow you to use this method. If you attempt to brine, and the salt concentration is greater than the brine concentration the turkey was injected with, there the possibility you can make the turkey saltier. It may be a waste of materials and time, to attempt to brine already enhanced meat. Also kosher poultry will not benefit from brining, since they are dried brined with salt during processing.
If the label states something like; "All natural. Up to 3% water added"; those can be brined.