on the floor of my living room and seem to roll pretty good, I don't know how that translates to idle quality, but it my indicate a smooth idle. Sorry about that, I've driven three cars with the JWt 400+ cams in them and I can't hear or feel a difference (in terms of idle quality) between them and the stockers. In fact, Seb of SpecialtyZ has a set of 500s in his new set up, and they also idle extremely smooth. My layman's guess is that most high performance cams for turbocharged cars idle fairly smoothly because of the mild duration and greater (than a normally asperated) lobe center spread. Take care, Mark