XRAY - Model racing cars

Bought an xb4 a couple of weeks ago to get into four wheel, choose the xray because it looked the most durable. So far so good after 2 nights if racing and a load of practice all that broke was a wing mount. I haven't really seen set ups for the track conditions I race on; Packed dirt, watered with a lot of loose dirt built up outside the groove, and the groove itself on the loose side, medium/large jumps with tight corners. So far the back of the car does step out a bit, looking for some suggestions to calm the car a bit, Pretty much using the manuals set up.