I've just remembered that when I fitted a new fuel filter that the fuel pressure regulator thing next to it started leaking. I found one in the garage that looked identical and fitted it. At the time though the car had dodgy leads and wasnt performing. I think the regulator I had in the garage was from a MK2 Astra 2.0 or 2.0 16V.
Will this cause problems? The car seems to run fine but I have no comparison because I didnt have it running properly before changing the filter!