Yep that's correct.

If I remember correctly then Map 1 ups boost by around 4PSI over stock with Map 2 upping boost by a further 2PSI again (for a total of 6PSI over stock). If you install a JB4 without the OBD cable then it will default to Map 1 - the advantage of the OBD cable is that it lets you choose between a number of various maps. There's an option for Map 1, an option for Map 2, an option to turn things off altogether (and essentially revert the car to standard) and then a couple of options for custom maps that would be vehicle specific and programmable by a tuner. All of these options can be controlled via the indicator stock (and I think there's even an option to control things through your phone).

Exact power levels can always vary but I reckon you'll see around 260-270hp on Map 1 with around 280hp on Map 2. The main concern with Map 2 is the exhaust gas temperatures (EGTs) which can get a little high. Usually you'd want to upgrade to a less-restrictive exhaust system (ideally including a sports catalytic-converter) in order to keep the EGTs low.