I have just fitted one of these, very easy to fit, most of the information can be found on the Apexi Web site - under meters.
The wiring diagram can be found under the old type, the one without the blue LCD display. If you are just using it for display and not as a rev/speed limt, then there is only 4 wires to connect. The rest of the values are calculated from these inputs.
If you are not so good at reading wiring diagrams, I have a copy that will help you.
Failing all that, contact DP Motorsport - Warrington as they are the UK official Apexi dealer.
Hope this helps,
The Apexi Rev/Speed Meter (optional G sensor) can perform the following functions;
1.Digital Rev Indication
2.Digital Speed Indication
3.Lateral G Forces Indication (optional)
4.F/R G Force Indication (optional)
5.Battery Voltage Indication
6.Trip Distance Indication.
All of the above have a peak hold value so you can view values later.They can also be viewed digitally, graphically or on a gauge type display.
The following calculations can also be calculated,where * = variable.
0-*Speed calculation eg 0-60 time.
0-*Distance calculation eg 0-400m.
PS calculation (including PS loss graph.)
You can also set speed limiter and rev limiter but that means a lot more wiring - 9 wires in total. But if you have a speed limiter already, this will override it.There is also an option to have the speed and revs flash when a preset value is acheived - slow down / change gear etc.
Note, when setting this unit up you have to program values in, such as wheel/tyre size, number of cylinders, type of pulse output from ecu etc etc.
In the few tests of 0-60 etc the meter seems pretty acurate but its only as good as the information you put in at the start, get that wrong and the timing/speed functions will be wrong too.
Hope this helps,