Bit confused about what i need and from where to give SO3 XXL some TLC

With an XXL (which has 9mm belts already), and an upgraded Z-axis, the only mechanical upgrade from Carbide Create would be the HD eccentric nuts:

(which are included in current Maintenance Kits if you need spares)

Some folks have found the Gates-branded GT2 belts worth paying extra for — check at BB Man, SDP/SI, Texas Belting, &c. (possibly also Filastruder).

For lubrication see:

and

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