Since you mentioned "Sportivo really lags at low rev ranges therefore if I can get some extra acceleration down low, that would be handy...", I must recommend a short ram intake (K&N, APEX'i), I've got the APEX'i Power Intake which is terrific. Makes an awesome noise and if I remember correctly, costed under $300 delivered from Japan. Intakes can be installed at home with a small range of tools. I too have a dyno sheet proving the power/torque gains against another Stivo with TRD intake. It's quite obvious that the TRD makes a higher peak power while APEX'i provides a better mid range.
With the suspension, King Lows are 35mm drop which means that you can still clear most of the slopes in Sydney . Ride is quite comfortable with improved cornering. I've got a set sitting at home so if you are interested, let me know.
My 2 cents.