Okay I now have a viable package. This is what the 3bar unit will look like. I will have pictures of the 4 bar package once I have all the electronics installed. I like the enclosure that the display is in now. It fits so perfect and I got it for around $6 on ebay. I just hope this guy has more. It is suited well for a windshield mount as shown in the pic and you can mount the map sensor close to the source and the main unit anywhere under the dash if you so desire. This particular one is slated for my friend!
The versions I make for you guys will be a bit better inside. Right now all of the ancillary electronics reside on on a prototype shield and it looks pretty messy. The next versions will have a proper printed circuit board and it will be universal for both the 3 and 4 bar models.
Once I'm done with these I think I'm hanging up the towel. It just takes to long for me to make even one of these and the return is not that great to warrant the effort. Once I'm done I will likely post the schematics, software, parts list and PC Board Artwork so you can make one yourself.