If you have any of the current generation Novarossi's you'll have to buy a pack of shims or source one accordingly.

Most of the current line comes in with a 0.80mm shim stack, broken down as a 0.30, 0.30, 0.20mm.

So you'll want to remove the 0.20 and replace it with a 0.10 for a total stack of 0.70

That will work well for an engine that is slightly past it's prime, running on 30% nitro, at typical elevation ranges.

As the engine ages, it loses it's compression seal and the heat of compression will be lower as well. You can gain some of the performance back by decreasing the deck height, to increase the compression ratio.

You can also cheat it by running 1-heat range hotter glowplug, but this isn't quite as reliable; but has a similar effect.