Aaron320iSmith

well ive just bought a 1985 320i for a grand (off my mum ). Its as stock as a rock and i need some info on modifing it. I'm planing a k&n with a heat shield, e34 m3 injectors, muffler from ebay and also a chip from ebay. Im not shore on what places in New Zealand make aftermarket extractors?????? I also will install a e30 m3 4.10:1 diff. I am looking for 250hp+ at the wheels. I know with this list i will be no wear near this so any tips/info would be grate. PS i dont want forced induction.