You have 2 options:
A sandwich plate on top of the oil filter. Eg mishimoto
An oil gallery plug as you mentioned.
These topics describe how to iirc:
http://forums.nasioc.com/forums/showthr ... ?t=2035192http://forums.nasioc.com/forums/showpos ... stcount=90http://www.iagperformance.com/Prosport- ... ropkit.htmBasically most senders (not the defi iirc) are too big to fit on the top rear bung, thus the need for a relocation kit...
Apparently the stock oil temp sensor bung under the alternator can be tee'd into, but iirc the rear location is preferred.
Some prefer the pressure reading from the oil filter location...
If you install a remote oil cooler one of the lines can be tee'd into as another option iirc...
To remove the bung use a quality (impact) Allen and if in doubt grinding paste to pack it out a little.
Or give it a technical tap before removing