I have the 1.4 the engine does have to work harder than most as the car weighs so much. I am not sure what you mean by rocking though mine doesnt do anything like that. someone said earlier in this thread that they liven up after 3000RPM and that is certainly true in the case of mine, not sure if it is the injectors firing more or what but it is noticable mine is quit loud when it is cold but that is normal and calms down when warmed up..