Oh how much I'd love if it worked like that, sadly nobody who has a say in this matter is listening at the moment. As it stands right now, we have politicians that have absolutely no idea about what they're doing making up factually wrong laws (the part with the specific weight being wrong) while providing close to zero communication, not even with fuel manufacturers. I don't know how the status of this is in other countries and can only report on what I was able to dig up on the german side of the story but it's not looking good at all.

The current state is:
After the 1st of February it won't be possible for people without a license (which you can't obtain for hobby use as of right now(edit: except for Sweden I guess), non-commercial licenses handed out before this change cease to be valid) to buy fuel with more than 12% nitro by volume, so less than 16% by weight. One year after that it'll be also illegal to own such fuel.
What can we do? Well, contact your politicians (they won't answer, I tried) and make them aware of the situation. Also contact all hobby shops in your area as well as any and every RC manufacturer or organization who still has an ounce of their business in the nitro world and ask them to also create pressure on the politicians. It probably won't change anything but at least you can feel like you tried.



To at least stay somewhat on-topic. As Roelof already mentioned, you'll have to lower the head gap (effectively increasing the compression ratio) and probably also play around with glow plugs a bit. The 0.1mm he mentioned are a good rule of thumb but it'll be different for every engine, you could contact the manufacturer and ask what nitro content the stock spacing was designed for and if they have any suggestions. Also, temp your engine even more regularly than you already did, it will run hotter.