i have had 3 classics and not 1 has had one car is a 95 wrx and its the big black box i need to no and can i take it off thanks

 

Looks like a resonator to dampen down the sound?
Older Impreza have them in the inner wing.
Should have no problem removing it.

 

i have and car runs like **** mate and it makes a **** load of noise

 

That's just a resonator to quieten down the induction noise. Early cars like yours had them fitted between the turbo and the air box.
Yes it can be removed (I did mine) but you must replace the two hoses that attach to it. One large one which can be seen in your picture and the smaller one underneath. Both these pipes need to fit onto whichever pipe you choose to replace the resonator with.

Here's mine for example.

 

The snorkus delete might be slightly different on the older cars,have a search for air box resonator delete,I remember reading you have to make sure solenoid and idle return are still piped up