[Sil-Eighty SE-K]

well to aswer your original question that is normal and shouldnt be leaking.... you would most likely hear it if it was leaking when u boost and you prolly wouldnt be able to make full boost either..... that red rubber is part of the diaphragm not a "seal" so to speak. In a way it is a seal but its not the part that seals in the valve shut...its seals off the diaphragm..... hope that helps..... also the springs are rated by your vacuum level (when idle) seeing as how it uses the spring to create the difference between the boost in the pipe and the vacuum in the diapragm when the throttle plate is shut..... at 10-14 psi on the T25 i run the 7-10psi spring