Had it a year and all of a sudden when i accellerate hard boost gauge flickers at about 10.5 psi when i know it runs purfect at 15.5 psi. When its on tick over -10 psi is ok as before. Anyone any ideas? I've took it apart and cleaned it but not helped.

bttt

May be anything but you could try the list below
1. May be the pipe is being crimped shut somewhere.
Check the entire length for any bends / grommets that are closing the pipe.
2. It may also be a bad connection to the back of the gauge or to the manifold.
3. Check for any small puncture holes on the pipe. A stone may have flicked up and holed it.

Cheers m8

Check it against another gauge. Does the car still perform exactly the same?