Is it possible to make at least as much horsepower as the Porsche 944 Turbo from the base non turbo 1987 944 2.5L engine?

the 2.5 engine will accept a super charger that will take it up to 220-250BHP but you will be sacrificing the longevity of the engine. all the oilseals, con rods, pistons, crank and cam shafts etc will not have been designed to take that sort of power. chances are you will blow the engine soon after fitting it. Try just mapping the ECU, this will give you a few extra HP. if you want the power of a turbo then get a turbo.