Well it's kinda cute reading all this back and forth on the 335 vs the M3.
Let's just say, that it's not all just about power. Just as a nicely loaded 550 is simply not an M5. A tunned E90/E92 335i will simply not be an E90/E92 M3
So if you got the cash, like the flash and want 400+HP -> Get the M3
If you don't have the cash or your better half will hang you out to dry if you spent that kind of dough on a car --> Get the 335i
But the M3 will beat even a Vishnu tunned 335