as far as i can tell there is no magic formula that has a universal application to all cars, regarding the use of swaybars or not and moreover the thickness of them. So how are you able to decide whether you need a swaybar or not? Some basic principles and trial and error is something to begin with. My ej9 has front a swaybar (23mm) and no rear swaybar. As stock the handling was a nightmare, a lot of body roll, understeerish, and exteme leaning. When i lowered the car and placed some sporty shocks (HnR bilstein) it was a lot better, day and night i would say, but it lacked the pure sporty turn in, the sharp body moovement and agile handling in general. Of course there are always some key points that can give you the right touch, like harder bushings, more aggresive suspension angles etc apart from a set of shocks and springs. However i have always thought that the MUST of setting a honda suspension are the right R swaybars! I am about to find that out myself as in a few days i am going to install an ek9 front swaybar and the ASR kit for the rear. I think that if you already have a decent coilover set (not extreme spring rates) hard enough bushings and the R swaybar combo, you will come close to magic ek9 and dc2 handling!
some general facts that you have to take into consideration as fas as EK's are concerned are the body weight, the weight distribution masses which is mainly located to the front,and the agility of the frame which is needed in order to make the double wishbones work properly. So if you want to avoid swaybars you need to have extreme spring rates and way too low center of gravity, meaningly low body. You can easily understand that these facts would compromise road use and comfort. So swaybars give you the opportunity for more street oriented spring rates and not extreme lowering. However this a general comment and i cannot prove it with mere numbers. So i would take as an orientation the R spec suspension set up and move from there!!
