thanks for that guys yeah most of the systems i use have very few rules i try to think like a horse trainer and base my systems around what a trainer would do to set the horse up for a race. all my system concentrate on one distance and do really well around carnival times.
Another system to test based around the principles mentioned above:

.1200 m only on sat metro
.third up from a spell
.first run back 1000-1100
.second run back 1200
.last start finished 1-3
.last start on a metro track