You won't need any upgrades for the axial .28, it performs just a bit better than the stock .28 in the SS kit.

OS 30VG or Axial .32 would required some upgrades.

You can run the axial .28 with what you have, but the metal diffs need to be installed.

After you burn up your first clutch bell using those alum shoes, get the mugen composites, much better and stickier.

You got some biased advice on the alum shoes. You'll just have to see for yourself what works best for you.

Use Robisnon Racing gear, anything else will get eaten.