Thank you all for the replies thus far

If I'm being honest, the main reason as to why I'm wanting to do Further is because my Maths teacher said that if I put the effort in, I could most likely pull off a good score. That too, I should find it a lot easier and straining than the work in Methods/Spesh. So I guess I'm doing it out of my love for Math, but at the same time a way to maximise my potential ATAR.
Oh really, only 2 Maths in the top four? That's something I was completely unaware of. So basically, only 10% of my third Maths subject Study Score will be used?

Is it still worth doing then? I mean is a difference of say a few decimals really that much? Cause if it's like a little difference, I guess it mighn't be all the effort, considering one of my other subjects won't even count anyway haha.
Skyline, thanks for the suggestion. I would love to, though doesn't that require completion of Methods 3/4 in Year 11? But then again, it might be too out of the way in terms of getting to the Uni etc.