Compression change after break-in?

[Pioneer]

How much change in compression can you expect from brand new piston/cylinder to when it's broken in?
How much from just swapping out a new ring with a light scuffing of the cylinder? Let's say you start out with 150 psi in both cases.

 

[cuinrearview]

10 psi isn't uncommon for break in. There are a lot of factors for scenario number two.

 

[Flavien Simon]

I am quite late here but here is what I found on a used 088 after I did some port work. The cylinder was showing some wear marks, but nothing very bad though.
Compression after re-installing with new rings : 140 psi,
Compression after honing the cylinder with fine grit a honing tool : 150 psi,
After one and a half tank of break in : 155+ psi