I haven't tuned it much yet besides downforce and transmission, but I'm trying to treat it like an oversized Kart, based on how easy it is to oversteer and lose traction. Throttle manipulation is key, and the steering is super sensitive so the inputs should be a bit smaller than when driving Gr.4/Gr.3 cars. You can play with the controller steering sensitivity setting in the Driving Options, if you can't tune it out. Also, there are plenty of folks who drive the Karts with CSA set to weak or strong, but don't use assists on other cars, simply because Karts are crazy difficult in this game. I don't see why these same people wouldn't make the same exception for the RedBull Junior since it handles similarly but with more power/speed.