Ran mine last season with 13/62 on 5s on a large track (80x230) and found it great on 4s it was also great, was able to get through the tighter stuff a little easier. The problem that I started to have was with the centre diff needed constant rebuilding mostly due to chassis flex, all this went away after I started using the tekno kit and I still run 13/48 mostly on 5s but that demands a careful trigger finger on track.