Nice ride and let me be the first to say welcome! We have alot of members here with m3 (e46's) and I am sure they can help you out alot. But I would bet that as far as performance and mods m3post or m3 forum would be your best bet! Did you just get your m3?
Arctic/Gray/Alum/Step/ZPP/ZCW/Xenon Mods: Interior Xenon/Xenesis Fogs/330 Chrome Exhaust Tips/Rear fog light switch/Blacklines/Charcoal filter removal/K&N Drop in Filter/Smoked Vinyl Overlays/Blackout grill/Pearlescent Hand-Brake/Happy Robot Mod/CF Door Pillars/OEM style Trunk spoiler/CF Splitters/Smoked LED Turn Signal