hmm... I come from an E46 320i (inline 6) which really had an uninspiring sound. I really enjoy the sound of my E90 325i, especially when on full throttle above 4000 rpm. It's agressive but certainly nothing like a Mustang or musclecar. I think it's just the way it should sound for this type of vehicle. Of course, I can understand the 330i has a better growl to it.
You can always consider an exhaust/muffler change-out!!
