-Yes.
335 + Dinan software + LSD = hard time for M3. Depending on dealer markups you could probably afford coilovers, wheels, better tires and a front StopTech BBK for the 335 and still save money.
$2k, Dinan
$2k, LSD
$3k, Coilovers
$4k, Wheels/Tires
$4k, StopTech BBK (only necessary for tracking)
= $15 in total mods (very roughly).
The best part is that the 335 would be 50lbs lighter than the M3 to start with. The coilovers and brakes would shave another 20-30lbs, mostly in the front which will improve balance. Wheels could also save weight, but won't since they will end up being wider and with bigger tires. figure 5lbs or a wash. So, after mods, you'll have a car with comparable suspension, probably better grip, better balance, almost as much HP (416 vs. 385), MUCH more torque (295 vs. 421), and 75lbs or so less weight.
p.s. I also think the 335 Coupe looks a hell of a lot better than the M3 too, a minor point relative to performance. I also appreciate the sleeper factor on a genuinely fast non-M.