Thanks to mr2u I went and bought one of these as even after having the ST for 6 years am still not sure sometimes if am in 4th or 5th without comparing the speedo and tacho
This is the one I bought
http://www.ebay.com.au/itm/121390182039?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITOnce I had all the fairings off and a look at the tightly packed wiring loom under the LH side fairing I decided to see if I could tap in just behind the instrument panel. I found that all the wires you need are here, not so tightly packed and easy to tap into with the plugs pulled out.
I just cut a slit in the rubber boot, poked the GPI cable through it and soldered the GPI wires to the correct honda wires.
These are the ones you want:
GPI Bike
Ground Black Green
Ignition switched +ve Red Brown/Black
Tacho pulse Yellow Yellow/Green
Speedo pulse Green Pink/Blue
Neutral light Orange Light Green/Red
The white wire of the GPI is grounded as part of the programming process and when this is finished just put a bit insulating tape over it and leave.
I mounted the unit underneath the little duct on the RH side of the dash using some HD double sided tape and also a cable tie around the cable which conveniently comes out of the unit on top at the back. Its in a good position visually and doesn't require drilling any visible holes.
When programming I ran a short wire from the GPI white wire and grounded this on the windscreen mechanism....it took me a few goes to program it and good idea to take it for a ride to check before putting fairings back on. When programming the fifth gear it flashed faster but didn't display a bar as in the lower gears, this was a little confusing.
I reckon if you are clever you should be able to install in this position without having to take any of the side fairings off, just the windscreen and the front dash cover.
On the road it works really well...it predicts where you are going with gear changes (ie assumes 4th is next gear change after 3rd) however if you have changed back to 2nd once you let clutch out it gets it right.
I love it, no more trying to change up in 5th thinking your in 4th or having to do mental speed/rpm calculations to know what gear you are in!
sD