Could I add a turbo are a supercharger?
 

I have a 1987 325 and was wondering if they made a turbo or a supercharger for my car??

yes, go with a supercharger for there will be no need to tear down the motor to put in different pistons, you may consider a cam upgrade and different fuel management. Sorry to say this but there is no easy or really inexpensive way to greater horse power. If you are mechanically inclined then this project is not cost prohibitive for looking around I am certain you can source parts from guys who have tracked similar set up cars and found themselves on the wrong side of a mishap. ( i.e. like blowing up a motor, getting rear ended or just wanting something faster). Happy motoring

who makes a supercharger for E30 M20?

powerdyne