I have an autometer one that measures both vacuum and boost. My complaint is that the travel of the needle is relatively small since it measures to 20" vacuum and 30psi of boost on the same gauge face....but its backlit, looks nice and is high quality. Got it (and a volt gauge) off ebay for about $25-30 apiece a few years ago. Maybe eventually I'll swap it out with one like the VDO pictured in one of the above posts....probably not though.

I connected mine with rubber vac hose with a T connector into the boost line before the switchover valve. I also used an orifice connector with a very small opening so in case the line in the dash leaks or the gauge leaks, it won't bleed off all my boost and cut my fuel delivery. Gauge works perfect. My car has around 11-12psi at full throttle under load.

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