Hi Lukacs, sorry, I havn't been on rcuniverse a lot lately so I discovered your thread just now. Very nice to see you building this engine, also as for Geof, very good work!
Nice looking diffuser, I still make them more or less by hand, using my simple 2D hand mill. Jealous to see you all with cnc machines ha ha ha!

As for the burner hole pattern difference between inner and outer liner, for the GR130 I would leave them against each other, not offset. This helped on my GR180 but have not tested this on the smaller engine. Maybe it works, I guess it won't harm, the idea was to give greater mixture of the gases and create more even flame.
I would start with flat holes, in the event you have high temperatures and have examined all other possibsle sources you might flare the holes against flame direction so as to "push" the flame forward and improving gas mixing.

Plug hole; I made this little boss as seen below and it's fixed by meand of 2 x M2 bolt. The boss sit's tight against the chamber where I mark the position with a feltpen through the boss. After this I drilled a 5mm hole in the chamber.


As far as the P160 chamber, this could work as well, there have been many idea's on chamber geometry. The chamber you have made worked on the GR130, it's always possible to improve things but you can do that in a later stage if it's needed. I tested many chambers as well, not the P160 yet and would be curious to see how it works.









Hope this helps.

Best regards,
Gerald

To flare the holes, push in the matching drill and bend it with the flare looking against the flame: