So I finally had a chance to dyno my car before adding on more performance mods.
Current performance modification: Eisenmann Race, aFe Air Filter, RE Pulley and RPi Scoops (if it counts)
Results: 338 RWHP on Dyno Jet.
Unfortunately I did not do a baseline dyno on my car. But according to Pencilgeek's Dyno Database, a stock e92 m3 should be pushing around 320rwhp give or take 5rwhp depending on weather conditions etc. If that's true, then approximate gain is 18rwhp.
Here are some pics! Special thanks to MFest and VF Engineering for setting this up.