Gday greenplastic, and welcome.
I am also a Rancilio Silvia owner in Perth.
Good water filtration is a must due to our water quality issues to start off. Use a 3 stage filtration system if possible, or at least use filtered water for your machine.
Apart from the obviously fresh coffee that you're already using, a good grinder will work wonders. What kind do you have?
The Silvia will reward with a great espresso if the quality of the grind, dosing, distribution and even tamping all align up well.
I chemical back flush at least once a week properly to maintain the cleanliness and longevity of the machine.