I own Vectra B 1.8 and last time on highway i took it to 205 km/h but no passengers and laguage. hope this helps... Last month i change gearbox, new tires, new exhaust and fixed some smaller problems. New software for car computer also... this had a lot of influece on power.
Use a screwdriver to remove all the screws and clips in the doors panel. Pull the panel away slowly, remove the wiring connections and the panel will come off easily.