Here's a picture showing where my EGT probe is mounted.

I would prefer the probe to be as close as possible to the centre of the exhaust stream coming from all cylinders.

IIRC the hole in the turbo inlet should have a bung there that connects to the smaller wastegate port and the boost port connects to the port closer to the outlet of the compressor housing

That smaller hose connection is to evacuate any oil that might accumulate in the wastegate diaphgram chamber.  There is a quite long and slender brass fitting on my Garrett TA0304B (1.6lTD application) that threads into the hole in the bottom of the compressor inlet and has a nipple that the rubber hose slips over.  Inside the fitting there is a small orifice.  I would guess that this piece is paricular to this turbo model or manufacturer.

It looks like from your picture that it is missing.  I would ask whoever you got the turbo from, or whoever "rebuilt" it, what happened to its missing pieces.  Unfortunately, spare parts for the Garrett TA0304B seem to be "off limits" for most Garrett turbo parts suppliers... they want you to buy a complete new or rebuilt one through the VW dealer it seems!  :?

By the way, for my pre-turbine pyrometer in the Garrett 1.6lTD turbo, I drilled and tapped the turbine housing right into the main turbine inlet port, with the wires for the thermocouple extending downwards.  That is another option besides the exhaust manifold, although you need to be precise where you put the hole and the direction as there is not a lot of room there.  I found also that the cast iron of the Garrett TA0304B had some very hard spots that made the drill want to wander around when it hit them, so be extra careful if you go this route.

thanks jake. i rbuilt the turbo myself and it didnt have those parts when i tore it apart. so if i wanted to make my own replacements. i need to understand what they are for. you said the small hole on the waiste gate is for excess oil in the waistgate.  so..does the hose/line running from under the comp housings blow air into that small hole on th waistegate to purge the oil out back? you would think it would draw oil out that hole towards the impellar, but why?or what is going on there? thanks for your explaination.

thanks jake.