Hello guys! those are the option parts i used in my XRAY XB4 on carpet all the time and most of them on dirt as well.

#362573 Alu Steering Plate 4-Hole
It reduces flex in the steering and makes the steering feeling more direct and gives you more Ackermann options to fine tune your car for any conditions.

#362478 Anti-Roll Bar 1.8mm
I use this sway bar almost all the time on carpet in the front and rear of the car. For me this gives the car the perfect balance between maximum steering and still super stable.

#362112-G & 363121-G/363111-G Composite Susp. Arms Front Lower - Graphite Made from the very durable and strong XRAY Graphite Composite makes the car more precise to drive and makes the car land perfect.

#335030 Differential Bevel and Satellite Gears
Those steel Gears make your Gear diff fell super smooth, unbreakable and will create a more direct feeling on power.
They also make the car fell more free.

#363351 & 363352 Alu Rear Upright
This part gives more wheelbase options, makes the car more precise and increase rear traction.

#366220 Independent Servo Mount
More precise steering and equal chassis flex.

#364901 Gear Center Differential
I really like this option for carpet a lot - It just makes the car easier and more consistent to drive without being slower.