Question about my Alfa

Hello everyone!! I’m new here and only recently Alfa driver and absolutely proud, that only by the way but now to ask: if I look at the technical data of the Alfas so, I always see at 2.0 16V 155PS, but mine has 165 hp how can I not understand that!! since someone vuekk has an explanation?? except with the new models (JTS) I found 166PS… since my Alfa construction year 2000 is not understood… Thanks in advance for your answer!!