I would just enjoy the 328... freakin' sweet car man!
As for turbocharging it... I with everyone else... it typically costs like $8000 bucks to successfully turbocharge a car thru aftermarket. Might as well just buy a 335i.
In addition, the 328i is running the aluminum/magnesium composite block. Somehow I don't see this block handling a tonne of boost pressure at this point. Not to mention, who knows how the block would handle the heat?