I just got one of these and so far I love it.
www.scangauge.com
It does three things, trip computer, gauges (12 standard, 24 custom), and a code reader. DW wanted something to monitor MPG and help improve that, I wanted a Transmission Temp and a Torque Converter gauge. Got it all with this. I tow with OD on, so I wanted to know if my torque converter was seeking and to make sure my transmission temp was within standards. Got it withthis.
It also has a Throttle Position Indicator, my first weekend I was able to get 1 MPG better than before. I am out for my first twoing weekend next week, so I'll report back.
