I have a 1987 944 and I recently started hearing a whining sound coming from the car, it can sound like it's coming from the hatch area and the pitch goes higher when accelerating. Almost sounds like a turbine.
Also, when the car is slowing down in gear a sort of scraping sound can be heard especially in second and third gear.

Anyone know what it can be?

 

Sounds like either transaxle noise or torque tube bearings. I would change your transaxle fluid and check for metal.