I've been playing around with the Mytach GPS watch from AiM, and frankly it's even better than the far more expensive GPS module that you can add to your Mychron 4.
The data from the Mytach can be imported straight into the Race Studio software and will produce all the usual features you would expect. You get your track map, limitless splits, speed trace, lat-g and long g. You cab use it to analyse lines and export them to google earth.
The mytach picks up satalites much faster than the GPS module and works inside cars and even inside some buildings when you are close to a window.
To find out more visit the mytach website
