Engine/Transmission (1998.5 - 2002) Boost gauge, smooth or twitchy?

[MRose]

I've always had this issue, if it is one. When I'm at max boost it fluxuates rapidly, after I put my OEM K&N filter in it would hold steady one lbs higher but I'm back to the twitch. Is this normal? Do I need to clean? Or BHAF?

 

[R-N-R]

A needle valve inline with the gauge hose cured my needle twitch.