i have some mods on the car already (see my sig)... i am thinking of a front lip and some other things... there are tons of options.. but i have to admit there are more mods for the 335 right now since the M3 is relatively new to the marketplace... also the one big thing i like bout the 335 is that mods are relatively cheap compared to mods for the m3... there's always an additional "M" tax whenever you buy mods for an m3... just look at how much a small part like m3 matte black side markers are selling for and you'll get what i mean.
Current: 2013 F10 M5 & 2013 GLK350
997.1 GT3RS (gone)
2009 WRX STI (gone)
e92 M3 (gone)