you're correct, they switch out your stock ones. i'm going to do them soon. i'm going to put 8500k in one side, 6500k in the other, look at them and decide what i wanna go with and then switch them accordingly. i plan on taking pics if anyone's interested.BigDon MO said:I am interested in brighter HIDs for my 04 SL. Do these 6500K bulbs just replace my existing factory HIDS. If not what is involved in upgrading to your brighter bulbs?