[5valve]

I did increase the breather hole to 1.5mm, as it was stuck with gunk. Tube is not blocked at the bottom, but joined into "Y" with other side breather, and then out.

Just had the head cut. Old piston squish was 2mm. With new piston was 1.75mm. Cut it to 1.24mm.

Since new piston is apprx 2/10mm higher, he said to use aditional base gasket, to correct port height to piston crown, as it results in 4 degree difference, which could affect top revs.
But I think, those engines aren't so picky, to really need an exact match to previous piston, since you can get them delivered new at very different settings, 200 rpm give or take.... Also exhaust port is perfectly lined up. From factory, one 0.5mm base was used. Will see how it behaves, and adjust if needed.

Head depth was also adjusted, have to measure compression.