brake pedal hissing a bit?

[MassSHO25]

Finally got my SHO running reliably again (damn CPS sensor lol) and now a new problem. After driving a bit the brake pedal gets a very hard feel to it and you can hear what sounds like air when pressing on it. Any help is appreciated

 

[CerberuS]

Do you have to press harder to have the same braking then before?

 

[MassSHO25]

Do you have to press harder to have the same braking then before?

yes indeed I do

 

[SHOck]

There's only one thing that can hiss that's associated with the brakes, and that is the brake booster and the vacuum line attached to it. I'd suggest you start by checking the vacuum line that attached to the brake booster (big, round black thing sitting between brake master cylinder and the firewall). If you don't know, the brake master cylinder is attached to the bottom of the brake fluid resevoir.