Using Tonemapscale doesn't actually affect the map, it only affects the camera's brightness. When you're tuning it down, the map's only darker to your perspective and in turn makes EVERYTHING ELSE darker as well. The fireworks will not glow on a daytime map.

If you want a darker map, then you'll have to decompile it in Hammer, remove lighting, and recompile it for SFM. However, there are some pre-compiled TF2 maps on the SFM workshop, if you're interested.

Thanks mate, but I gues I need to do this an other way, I have no idea how hammer works at all and somehow copying the particle like over 10 times make it already look brighter. The disadvantage is is that it laggs like sh*t because i have a slow computer. Still thanks though :D