If you purchase a Cobb AP, then you can download maps from their site for both the Cobb SF & AEM intake.
In terms of HP ... per Cobb (for which they supple impressive data and maps) the intake will offer a little more HP (301 vs 309 HP and this is factory stated HP with added % per Cobb not dyno'd). I think the greatest benefit from the intake in an otherwise stock car (expect Cobb AP tune) is more torque (forgot the figures), higher AP set Boost (17-Stage 1 + SF vs 16-Stage 1 w/o SF), and faster spool up time for your turbo. At least this is what I've read and feel when I drive my car.
I actually, temporarily, un-installed my Cobb SF intake system after being annoyed with the noise that it made during the daily drive (the "sucking" noise under normal acceleration). However, have since re-installed it because of the performance difference .... and am just getting use to the noise.
hope this helps.
2011 WRX Premium Sedan - WR Blue
Cobb AP Stage 1 93 & Cobb SF Intake