it´s an old issue, but anyway I want to care about it. On my 94 BRM there´s a hissing noise when appling the brake pedal, sort of smacking. I guess it´s something with the brake booster, not only the noise (what unusual on german cars), but rather the brake effect comes a bit hesitantly. The first small amout of pedal travel is easy force with this noise, then - once pressure increases - the noise disappeares and the brake effect comes very progressively. Sometimes it´s difficult to meter the brake effort, particulary if you brake very quick, it´s more an unwanted emergency stop. Not really bad, I´ve got use to it, but anyway a bit strange and if I could improve the situation I would do. Any ideas?