I´m trying to decide on wich airbrush i should purchase. The thing is that I have an Aztek, but i want to upgrade my toolbox so to say. I use Mainly thined acrylics and want to achive fine details. Could someone recomend me wich tip of the airbrush I should choose.

I would go for 0.3 for two reasons. First - nozzle is harder to damage or brake, second - 0.2 nozzle gets stuck with paint really quicker than 0.3 nozzle. Some of the acrylic, like MM, are really pain in the a** to work with with 0.2 nozzle.
Recoomend - use 0.3 airbrush and sharpen the needle a bit so it sticks out of the nozzle a bit more, you'll get really really finer lines like that. I have two 0.2 airbrushes but most of the fine work I am doing with 0.35 nozzle with sharpened needle.

thanks....

I had an Iwata HP-B with a .2 nozzle and traded it out for an Iwata HP-C with a .3 nozzle. I get more use from the .3 nozzle. The .2 was to small for practical applications using acrylics. Cheers, Greg.