Question about my boost pressure

[SeanGSR]

Hey guys, I've just installed a Greddy Profec spec 2 boost controller. The vacuum line going into the back of it for the boost pressure reading is the same vacuum line which runs my turbosmart boost gauge, however for some reason both units are displaying dramatically different readings. For example my boost gauge will show about 17 psi where as the boost controller unit shows around 22 psi. Is this normal to show such a difference in boost? And which reading would be more accurate?

Any help is greatly appreciated, thanks!

Edit, line is ran straight from intake manifold, 4g63 motor

 

[Vegas Smith]

Hmm, doesn't seem normal to me but I've never used a Greddy Profec. I guess check both lines to see if there are cracks or leaks.

 

[Melbowski]

Definitely check for leaks to be sure. Just as an aside, what elevation do you live at? Some electronic gauges will zero themselves at the current barometric pressure so your boost reading remains consistent, whereas manual guages and some electronic gauges are calibrated specifically at sea level and can't/don't change. This can cause a disparity between two gauges, as they'll report different readings from the same input. Just some food for thought.