Brake problems

[84GT350-1]

I have just finished my 82GT and took it out for a road test but found out when I push the brake pedal I hear a hissing noise and the engine also revs up a bit. I am assuming this is the power brake booster leaking vacuum. Is this available thru part stores Or something that will have to be sent in for a rebuild??

[Stang951]

Sounds like the booster is leaking. You can get a new one from most parts stores. Or you could just upgrade the brakes and get a new booster, newer mc, front calipers and rear calipers.