It's a question I don't really know the answer to! There's no definate easy soloutions for the 1.8s it seems.

I have used std pistons skimmed myself in the past. Not ideal, but works and is cheap

People use spacer "decompression" plates with std pistons, again, not strong, not ideal, but seems to work

Accralite pistons, not come accross these myself, but heard nothing good, and lots bad about people using them in 1.8s

Nothing from Vaux like the Calibra pistons will go straight in

Arias may make pistons for the 1.8, probbaly a safe bet there! I'd do that.

It's a shame 1.8s are everywhere, cheap....just doesn't seem to be a clear-cut soloution for them