Well, I installed sensor for boost gauge to my Magnuson SC manifold, gauge is showing 18 vac with little to no boost and car is on boost by sound and feel. What values should I see, vac and boost? Car is 05 GTO M6 and dyno tuned at 8psi. I observed very little if any boost on gauge even at WOT. I hope this is a gauge issue. I have contacted SpeedHut to check gauge zero and accuracy. Any thoughts, thanks.