Right. Pulled up from work today, parked the car up the drive and let it idle for a minute or 2, but for some reason i pressed the brake to which i noticed the boost gauge move. The car idles bang on 20 inhg without any movement on idle now but, when i started to press the brakes, the vacuum was creeping up to 17/18 inhg, if i kept pressing the brake the needle would just keep flicking up and down between 20 and 17 inhg. Now to me this isn't normal and shouldn't happen, it should sit bang on 20 inhg regardless of the brakes! I do remember Andrew having to replace the brake pipe behind the heat shielding next to the bulk head, cant remember what the proper name for it is, could this be at fault?