i got a complete motor ( no history! lol) to put in me s1. it has a later type water pump on it. changed the water pump to the s1 one,stuck the engine in the car, now the inlet manifold doesnt fit?!. is the head different on a s1 to a s2?, as in ports un stuff?. ifso, is there any other differences that i might be overlooking that might catch me out?