Fx impact x .25 whistle?

It does but it's not supposed to. Either clean the reg or up the pressure. My impact was making whistle really loud. As loud as the gun shot, no kidding. I was gonna clean it but decided to up to pressure from 140 bar to 150 bar and it stop making the whistle so I just left it at 150 bar. First try to up the reg pressure. If it doesn't work then you need to clean it 
 
fx impact x cal .25 is it normal to hear a whistle in the regulator every time I fire the rifle ??? Thank you for your answers ??

check the speed and consistency with a chrony, if they are OK, leave it like that, its only the plenum refilling with regulated air!!!

I think that in those who prepare your rifle because, a I have .25 standard y never heard anything.