I use a sunpro 2 inch that I don't mind, I had to make a fitting that T'd off my brake booster bung, but that was just a trip to the hardware store. Then run it into the cab onto a piller mount that I hated but needed. I'm not sure of the accuracy of these gauges, they're not total crap, and from what my MAP reads it seems pretty on the ball. I do pay more attention to my plx wideband though to really know whats going on...
EDIT
http://www.dsmtuners.com/forums/newbie-forum/355953-sunpro-boost-gauge.html
these guys seem to like them to, but they also use turbo plumbing parts from home depot, something we syty guys would never do....(don't look under my hood)