I'm considering buying a nice looking BMW 520i automatic '89 model. It's driven 145000 km. (not miles) and I can get it for around 7500 $. Now the only thing I am not ok with is the engine because model '90 is 21hp more powerful! So is there a way to make the '89 engine as powerful (performance chip or whatever) and can anyone please tell me thoughts of 520i and it's motor and reliability and such stuff... Whether or not to buy it.