Mate of mines lights are absolutely p*ss poor, headlight almost yellow,back light very faint as is the brake light - speedo bulbs OK though

Runs a 12v 25/25w for the headlight, led rear & a "normal" speedo bulb , ducatti CDI & regulator & a BGM stator (possibly MK1). Any pointers where to start? He doesn't want to go down the DC route