XRAY - Model racing cars

Hi everybody

I am new in this forum as I am also new for xray and 4wd . I recently bought the new xb4 2014 and I have a question that any of you may help me to solve.

I have been reading a lot about the importance of the slipper clutch setting. As I am going to be using my car in high byte tracks (carpet), I think that the slipper clutch setting is critical to do not damage the drivetrain.

I have experience in setting slipper in 2wd, but I have never done it in a 4wd, so if someone can explain me step by step how to do it, I would really appreciate it. By setting I mean how to adjust the slipper clutch depending on the track surface and characteristics. I have already read the manual and I know the recommended range (5,7 mm- 6,3 mm), but I assume that this range is illustrative/guide and I need to fine tune the slipper clutch on the track. This fine tune setting is what I am asking for.

I also take the chance to ask for the optional diff gears. I am going to buy some spares, which include the diff gear (as I am going to be driving on carpet, I think is good to have a replacement for them). So I was wondering if it would make sense to buy the optional gears (graphite or metal) instead of the composite ones, as spare. Which are the pros and cons of graphite and metal gears vs composite? Does someone have experience with them?

Thank you very much and really looking forward for your responses.