My 90 xm 2.0i, have new spheres, (I lost my mind and I change-it all, they were all without preesure). I ear a wistle some times, (continuos when i put the car On) but since last weekend, the noise is not the some wistle and is more audible, and with a low frequency of sound.

Any ideas?

Did you slacken off the pressure release screw on the regulator, if so, did you screw it up again?

Peter.N.