DirtyLopez wrote:I just wonder whats the story with this oil catch tank...
Is it worth to fit it? What actualy they do? Is it a performance mod or what?

My understanding of an Oil catch tank is that it basically stops oil from blowing back through the intake and around your engine bay - works best in conjunction with a crankcase breather filter.
May be useful if your FTO is doing a lot of track days or you have a turbo on there (i.e. engine under a lot of stress) but its not really a performance mod.
It wouldn't be high up my list of mods but I could see how it would be useful alright. Money better spent on an upgraded fuel pump and/or fuel pressure regulator if you don't already have one.
BTW - did you see one for sale somewhere?