The figures that a company gives, are not on the wheel...the hp of a car, is the power of the engine but not calculated on a dyno. On a dyno, you are lossing some power and you are right.
this happens with all cars, not only with Alfa. So now, we are ok....now, as far as my car, there is of course some variance to figures we got but not much. A car saying 185hp may give 160hp on dyno. A car saying 400, may give 350 on a dyno as we have the distance covered, gear rations etc. The manufacturers are calculating only engine power. Same applies to motorcycles. I have a ducati 998S. It gives 136hp according to the manufacturer. i put racing ECU with termignoni racing exhaust, racing air filter, lightweight racing flywheel and some other minor mods and gave 134hp on dyno. this proves what i beleive. Engine power is one thing, engine power in the car on the dyno, is another thing. mine was remapped and a K&N air filter and i dont beleive, whatever is said, that the car has only 160hp. Before i used to have a mini JCW, before that an alfa 33 16V. my friends have very fast expensive supercars so i know how to appreciate the speed and power. The first day of remapping, i saw almost nothing. the next day, the improvement was significant....as i dont use her every day, will see how much faster will feel in the next days. i do not expect miracles and the car is not flying but is try to fly in comparison with how it was :-)