Umberto, I'm no lamp expert, but MH aka HID will color shift over time. I had a small saltwater reef tank and new MH bulbs would take about 100 hrs to fully color adjust and then they will degrade over time. That's why its best to change both bulbs at the same time on your headlights.
Also in this case, a change in the ballast could produce a slightly different color light w the same bulb.
I would try switching the left and right bulb on the headlights to see if its a ballast issue before just assuming its a bulb issue.
Also in this case, a change in the ballast could produce a slightly different color light w the same bulb.
I would try switching the left and right bulb on the headlights to see if its a ballast issue before just assuming its a bulb issue.
