Intake/Pulleys are a great way to increase HP on NA platforms:
2011 BMW M3 (Alpine White)
Dynorun 21: Baseline
Dynorun 30: Macht Schnell Stage 2 Intake Charge Kit, Stock Exhaust
Dynorun 33: Macht Schnell S65 Performance Underdrive Pulleys, OEM Intake, Stock Exhaust
Dynorun 36: Macht Schnell Stage 2 Intake Charge Kit, Macht Schnell S65 Performance Underdrive Pulleys, Stock Exhaust
Dynorun 52: Macht Schnell Stage 2 Intake Charge Kit, Macht Schnell S65 Performance Underdrive Pulleys, Challenge Race+ X-Pipe (Catless), Akrapovic Slip-On Titanium Exhaust System
More info and additional dynos can be found in this thread:
http://www.m3post.com/forums/showthread.php?t=567651
Feel free to contact me directly if you have any questions.