I had very pour lighting from the GT when I first had it. One of the lamps wasn’t pointing straight ahead and pointed over the other lamp and both where low. This made a very bright spot just in front of the car which dazzled me but didn’t illuminate anywhere were I needed to see.
You can check them if you can find approx 15m of level road in the dark. The top horizontal line of the beam pattern has to drop 10cm over 10metres. To check them stand next to the lamp and note the position of the horizontal line on your leg, walk 10 paces away and see how far the beam has dropped on your leg. To see if the lamps are pointing parallel and straight ahead find a wall to park perpendicular to. Drive towards the wall and the lamp patterns should not move side to side, only up as you get closer to the wall.
GT lights aren’t the best by a long way, I find they have uneven patchy light. The Fiat Mk2 Punto I have has projector lenses which give a very even light spread and are at least 3 times better than the GT.