It will not be as close as you think. According to what somebody mentioned in another post, the new M3 is going to be ~100 lbs lighter (carbon fiber roof, light weight V8) than the 335i and with 420hp, it will destroy any Procede equipped 335s. Heck, the e46 M3 is faster than a stock 335 by a bigger margin then some of you are lead to believe.
I disagree completely...first of all I own a 2003 6MT M3 coupe and a 2007 335i 6MT sedan. My M3 has PSS9's, full exhaust (incl. headers), intake, software and weighs in around 3,250 lbs. Stock for stock the M3 has the edge after about 70-80 mphs and definitely has a leg up in the triple digits. My M3 and my 335 are pretty close right now up to 100 or so but the M still pulls after that but it has about $10K in mods. The 335i with coilovers and a Procede will be very competitive with the upcoming M3 (LSD aside).