What hks part is this?
 

Had the car for about 4 years now its a my1995 wrx.

the part is about 1.5 inches in dimater and 0.5 inch long. It has a pipe from inlet (input?) and a plug ( output?) with 4 wires i think. It's gold in colour and what is it? as it came with the car when i imported it.

thanks lads.