Ok so I can't really find any info on how to read negative boost as vacuum. I've heard that the negative number x2 is vacuum. My gauge consistently reads - 8.9 ~ - 8.7 at an idle. I assume that means I'm at roughly 19-20" of vacuum.

I believe I have a vacuum leak but can't find a factory spec! I'm under the assumption that oem is 22-23" and hoping this will help my lean condition.

Car idles beautifully, but after 3k RPM at wot the car hesitates and feels sluggish in the top of the RPM range. Catless obx header, 2.25" straight pipe right out the back, no resonator, no bends (battery tray had rotted so was previously deleted)

 

I can't help you with the Scan Gauge, but if your running normal at idle and lean at WOT, make sure you have a good snug fit for the vacuum line to the fuel pressure regulator. Engine heat can cause that line to develop slight leaks.

 

I zip tied both booted ends of that plastic hose on a while ago when I first started looking for the solution, it brought me up from -6.6 in vacuum.