TII oil pump on n/a engine.
 

I seem to recall reading somewhere that the TII oil pump flows more than the n/a oil pump, and that the TII oil pump is a direct swap onto an n/a engine.

Assuming the above is true, is it worth it? I plan on doing autocross and maybe the occasional track day, but it's not a serious race car. The engine (S5 n/a) is on a stand, and I plan on replacing the front cover gasket, so doing the pump would be easy while I'm in there.

true on both counts. if you already have one, then by all means put it in. if you're asking if you should specifically buy one because you'll have the front cover off, then i'm really not sure. i mean i believe every little bit counts (if you can get the parts) but i wouldn't impose that on you.

As above, true.
Personally, given the pain of swapping the oil pump while the engine is in the car should you have to later, and the consequences of an oil system vs. the cost of a new pump, it's certainly not a bad idea while you have the front cover off.
But, it really comes down to the existing pump. Is it reasonably new, or is it the original pump or of unknown origin? It's it original/unknown, I'd put in a new one just to feel better.

the Turbo pump is larger, so it flows more oil, which is good.

if you've got it apart, put the turbo pump in, but i wouldn't take it apart just to put the turbo pump in, too much work for that

I´ve been thinking about some thing. Pump has fixed volume and flow is directly tied to engine RPMs - till pressure regulator starts bleeding excess oil back to the pan. So when we will fit bigger volume oil pump, we will hit regulated pressure in earlier RPMs but then, flow is very same, granted that we use same regulator.

I know that this is done regularly, but I think there are some misunderstands in flow, pressure etc.