The Omni 3 bar MAP sensor is most commonly used and is good to about 29 psi of boost (have to account for atmospheric pressure), which is more than enough for a daily driver. A 4 bar sensor is therefore highly unnecessary. Whichever one you pick, just let your tuner know so they can enter the scaling value into the tuning table.
http://omnipowerusa.com/store/Subaru...nsor-c11282089