On a 5125 rear shock do you mount it with the writing correct way up which would put the boot on the bottom?

the boot goes on the bottom

It doesn't matter

does that effect the valving in any way

Boots on the bottom, but that is just my opinion.

I asked myself these same questions last week, then just decided lettering should be correct, so boots down.

i think if it mattered, they would have noted in the instructions or on the shocks. i know some shocks only valve correctly or lubricate correctly if a certain side is down. so id say whatever way you want with these

They can be ran both ways. Boot up or down.

Nor-Cal Nick