I had the same the other day. Coming from a clio 172 to a 350z I'm about 15mph slower around a large motorway roundabout near me. I had no problems with the traction coming on but the back end felt very light. Just held it there all the way around. Felt that if I had applied more power it would have spun out. Iv had a play with traction off but not at high speed yet. I'm just slowly getting used to it. When I had the clio at first I was young and daft but after owning it for 3 year and slowly getting used to it wow I could make that car dance, it was like the car was a part of you. I'm just hoping eventually ill get the same feeling in the z