Hey Matthat,
I don't have answers but I'm in the same position.
No. 1 on my list is to install stiffer sway bars. I'm thinking Whiteline 24mm front, 22mm rear.
No. 2 is lowering. In my case I don't want to slam it, only after a small amount of lowering, e.g. 1". I was thinking King springs but their website says "DUE TO A LACK OF SUSPENSION TRAVEL OF THE SHOCK ABSORBERS, WE CAN NOT MANUFACTURE A LOWERED NOR A RAISED HEIGHT FOR THIS VEHICLE" so I need to research this some more. https://kingsprings.com.au/catalogue/vehicle/837/subaru-forester-sh-without-self-level-rear-3-2008-2013
No. 3 is exhaust. Mine is currently bog standard. I haven't done any research on this yet.