phase2 to phase 3 crystals

[Piggy]

plug and play, as said above you'll need to swap the adjusters off. you don't have to change the stalk but i think if you don't, the dipped beams are on when you have high beams on otherwise. so worth just popping a p3 stalk in really

Its the opposite.

You want high and low on together but with a single optic with a h4 you run the risk of burning the dual filaments out...no such issue with twin optics.