A common problem with boost gauges is that they can buzz whenever they read positive pressure, something that the SuzukiSport gauge had done since its installation. The reason for this buzz lies in the natural pulsations in the intake manifold caused by the opening and closing of the engine’s inlet valves; smoothing out these pulses as they travel up the vacuum pipe to the boost gauge cures the buzz, which isn’t actually as hard as it sounds.
There are so-called “No-Buzz” t-pieces which you can use to try and dampen the pulses but a bit of Googling reveals that they don’t always work and that some form of adjustable restrictor is better to “tune in” to the particular pulse of individual vehicles. Pneumatic flow controllers are relatively cheap (I paid around £4 for one via eBay) and do the job really well – they come as push fit items which make them very easy to add to your existing hose setup and have a lockable restrictor which you can wind in and out really easily.
A quick run out along some quiet roads is all that’s necessary to dial the controller in – just wind the restrictor in until the buzzing stops. It’s very easy to tell if you go too far as the gauge becomes very laggy and slow to respond.