Something neat I came across for the 8th gen civic is a scanguage. Its $169 and plugs into the OBD2 port. Its a nice install with no tools needed. I fed the harness into the gap between the lower and upper console and velcro it into place.

It lets you see water temp, throttle position, ignition timing, gas mileage, miles to empty etc. You can even set the LED's to be the same red as the SI gauges. Its well worth it. http://www.scanguage.com/