What option parts should I consider buying with a new kit?
None are required but we recommend the following:

Springs:
Low Grip Track:
TKR8772 – Yellow Low Frequency Rear Springs and TKR8762 – Grey Low Frequency Front Springs

Low to Medium Grip Track:
TKR8773 – Orange Low Frequency Rear Springs and TKR8763 – Black Low Frequency Front Springs

Medium to High Grip Track:
TKR8774 - Red Low Frequency Rear Springs and TKR8764 - Pink Low Frequency Front Springs

TKR5199B – HRC Rear Hubs (L/R, CV or uni, EB/NB/ET/NT48/48.3) - Improves stability of the rear on mid to corner exit. Able to be on power earlier on corner exit.

TKR6146 - CNC Delrin Shock Cartridge Set

TiNi Shock Shafts
-TKR6017T (front)
-TKR6061T (rear)

This car is very durable. Here are the spare parts that I recommend you keep on hand:
TKR5020 – Hinge Pins (inner, front/rear)
TKR6061T – Rear Shock Shafts w/ TiNi Coating and TKR6017T – Front Shock Shafts w/ TiNi Coating
TKR5286 – Front Suspension Arms and TKR5184 – Rear Suspension Arms
TKR5194 – Spindle Carriers
TKR6009 – Shock O-Ring and Bladder Set (for 2 shocks)

Tips and Tricks

List of Vehicle Setup Adjustments and Build Tips can be found here. There are several videos and articles detailing the building of shocks, diffs, camber links, etc.

Page 17 Step M-3
Put the screw in upside down so that the head of the screw is in the hex spot that's molded into the spindle. This will aid in clearance in full droop / full steering.

Page 14 Step K-2
Use no less than 4 shims on the steering spindle to limit steering throw. I actually just use one 2mm ball stud washer from my 10th scale stuff since each shim is .5mm.

Warranty Policy:
Tekno RC is the only company in the industry that will give 50% off of parts if returned to them using the General Warranty return policy found on their website. The parts can be lightly used or completely abused, as long as the part is still being produced it's covered!

Piston Drills:
Some of our setups recommend using pistons that are enlarged. For instance 4x1.9 or 3x2.0. To drill the pistons we recommend the following:
GMK Supply Piston Drill Set
16PC Metric Bit Set Metric Sizes 2.00 to 3.00 MM.

Setup Sheets:
Setup sheets for all of our vehicles can be found here.