hi i got a subaru 1996 sti we av been told a vacaum pipe as come off is there 1 on these

 

The brake servo (big round thing behind the master cylinder uses manifold vacuum to add assisting hydraulic pressure (so you don't have to press brake pedal too hard). I take it this is what you mean? Check it to see if there are any obvious pipes off (I'm not sure of the architecture of the brake servo - never studied one).

 

i dnt know i have never worked on 1 worked on other cars

 

Other car with brake servos will follow pretty much the same pattern - brake servos aren't Impreza specific, lol.