Quick question about my BOV
 

I have Greddy Type-S I beleive (attached).

Where do I connect hose from UIM? Nipple on upper pink half?
What is other niple for?

Thanks!

Yes you attatch the vacuum line to the nipple on the right hand side of the pink top. The top should just be an adjustment screw.

what he said. the top is just an adjustment screw to change the sound, well not the reason for it but thats what people use it for, hehe. just use the nipple on the side.

I understand that it's screw. There is 2 nipples. 2nd one comes from aluminum bottom half (kind of seen on a picture)

I wonder whats it for?

Found this...

The diaphragm is pushed downward by a spring. The tension on this
spring is controlled by the adjustment nut at the top of the BOV.

The valve opens when the diaphragm moves upwards. This happens when
the vacuum at the upper nipple (normally connected to the intake
manifold) is enough to overcome both spring tension and whatever
pressure is present at the lower nipple (connected either to the
atmosphere or to the compressor outlet). So the valve's position is
determined by the differential pressure between the two nipples.

(Technically, the pressure at the inlet of the valve is also involved
since it pushes up against the spring too, but let's assume GReddy
designed it so that effect would be minimized by giving the diaphragm
a lot more surface area than whatever the seal is at the valve seat.
This seems reasonable since it would explain the hat-shaped top of the
BOV.)

So. If you leave the lower nipple disconnected, you end up in a
situation where manifold vacuum alone determines when the valve opens.
To keep the valve closed at idle, you have to set the spring so it
won't allow the valve to open until you get to around 10 psi of
vacuum. This is pretty extreme; it's easy to get compressor surge with
less vacuum than that. So you can either set the spring to shut the
valve at idle, or set it to prevent compressor surge. But probably not
both.

But if you connect the lower nipple to a pre-throttle boost pressure
source, then you can set it up so opening requires both high vacuum in
the manifold and high pressure at the compressor outlet. So say you
set the spring to, say, 11 psi. Manifold vacuum at idle will never be
that high. But, if the turbo's making even the slightest amount of
boost, it'll push over the limit and let the valve open. And if the
turbo's making more boost, the valve will open with even less vacuum.
So you have a good chance of setting things up to minimize or
eliminate compressor surge while also minimizing or eliminating leak
at idle. You still end up with a little more lag since you're not
equalizing pressures across the compressor wheel, but that effect is
pretty small anyway.

So, there is nothing to do with main inlet?(from Y-pipe)

I bought car like this and forgot which nipple hose was connected. Now I understand that it's top one. If I'm to route another one - what is the best way to test it?

Where is
?

It's a vaccum line. You can get it from anywhere but make sure the one you lost lisn't lsot forever. it = boost leak

I don't think I lost anything. I will connect vaccum line from UIM to top portion of BOV. There was nothing connected to bottom (OE style). Stock BOV has only 1 nipple