well, unless names are different in the states, the 325tds is a 145bhp car with a normal turbo diesel with intercooler.
No direct injection, so unless you want to swap the engine with an E46 3.0, you won't be able to use the alpina tuning.
Mabe they have some parts for your car, but i'm not sure.
All that i know is that chiptuning will get you at 188bhp. And if you want to further change the engine, i would suggest looking at the E46 engine