Here is my setup sheet for the TRF 421 in the 21.5 TC class. Track location is RCP in San Marcos, CA. This is a small, technical, low grip asphalt parking lot track.

The upper arms have been converted to fully adjustable using rod ends from the 3Racing Cero and Awesomatix ball studs. This was done only because the stock arms start to bow upwards in as little as 15 packs. Caster can be set to the same value as stock and the sliding caster adjustment used as normal.

I recommend a 3.5mm shim on the hub for the best range of camber adjustment. The AMX ball studs are 4.8mm diameter and fit the best in the 3Racing rod ends. You will need to cut four of the AMX ball studs down to 5mm thread length to prevent the threads from hitting the shock tower when using less than 1mm of shims on the inside. Keep the extra set of full length ball studs if you use more than 3mm of shims on the inside.

Parts list:

3Racing
2x SAK-C173 (rod ends)
1x SAK-C139/V2 (6.5mm length, 5.2mm diameter ball stud)

Awesomatix
3x ST24 (ball studs)

Tamiya
4x 54248 (3x23mm turnbuckles)