Yup, there will be some oscillations in boost pressure that cause many needles to "buzz"... several vendors (Draft42 for example) sell a boost hose T with a restriction specifically to damp this annoying noise. I have one... works great.If you can't find one locally Concept 1 in Calgary has 'em... 3/4s of the way down this page:http://www.concept1.ca/engine%20gauges.htmIt's their part number 42D 42-003 .
Or stuff some cigarette filter cotton into the pipe until it shuts up. The buzz is the guage trying to respond to the 30 odd sucks a second as the engine cylinders each breathe. The gears in the guage will wear out fast too.
Pipe - what pipe??
Reporting back... I did the "melted tee" mod. It does work and is very easy. It doesn't take much of a hole, though. I used a pin, and only pushed it in maybe 1/16". Have just the faintest buzz now - not really annoying.