Expansion joint, grout or not to grout

[lighthoos]

Hi,
I have an aluminium expansion joint running through 600x600mm porcelain tiles, my question is whether its best to butt the tiles against the aluminium edge or to allow a 3mm gap for grout either side of the exp. joint.
My grout is a dark grey colour and aesthetically i think it would look better without it, but is it best practice to grout along the expansion joint? Thanks

 

[One Day]

Definitely grout. Reduces the risk of edge damage from the MOVEMENT joint!