Adding this and that, make minor improvements.
Avanza is NOT Grand Livina - it does not drives like a sedan, Do NOT expect to change that with modding.
I drives a 1.3 Avanza and I have friends that makes changes like those and honestly only minor improvement.
If your Avanza only carries 2 people including you, expect it to bounce "like a rabbit" on the highway.

Avanza is not 100% built like a MPV, it does have the characteristic but its suspension is that of a van/lorry.
It was the cheapest 7 seater MPV around at that time, very soon to be challenge by Perodua MPV.

Ask you father/parent to trade it in for the Perodua MPV.

The Perodua MPV is expected in Nov 2009 but there are some that said Sep 2009. The price is below S70000, some put it at $66000.
From the pictures I had seen, it is a stiff challange to Exora.
It is smaller than Exora, some said Avanza size with a 1.5cc engine.

Search the web for the pictures and you would like it.
Do mot spend your money on changing Avanza parts, same it for Perodua MPV.
When we buy a car, it should be what we expect and not trying changing it to something else.
You know what I mean if you see those people who tried to change the Wira into Evo.

Well just ask your parents, Perodua MPV or Toyota Vios.
Since the Avanza belongs to them, they have the final say.
There is a reason for them to get Avanza in the first place.