Hi Nedro,
I don't think the alloy gearbox is a must have option. The original one with the 4 screws is good enough. I don't have any problem with it.
In my opinion, useful options are:
- 5° front hub carrier
- Complete springs kit in order to tune the car with different track conditions
- Some spare that may break such as front arms
- Front Titanium turnbuckles much more solid than the original gold ones
- 78 spur gear in order to move the motor more to the rear axle
And that's it! Just drive...
