I just found out today the head is cracked on my 1990 325i. Other than buying a new head I was wondering what options, mainly what engines, could I put into my car. What model year engines could go in my car at a reasonable price and amount of work. I would be interested in putting the most powerful engine I could, but I dont want to do something dumb that would cost more than the car is worth, and take me months to get my car working again. Any suggestions?