Remember, too, that more roll stiffness will drastically affect the handling balance of the car. I'm not saying that's bad, just different. Make sure you have an objective in mind.... "better handling" is not only vague, but objective. Also, sway bars are only PART of the equation... bushings, alignment, springs, struts, etc all play a part.

For example, Auto-Xers (circa mid '80s, racing 3G/4G Civics) used to completely remove the front sway bar because they WANTED the body to roll. Some road racers would use 28mm (sometimes larger) bars.

For "spirited street driving" I prefer stock bars with slightly lowered (~3/4") springs and fully adjustable struts. I want compliance with a moderate amount of additional damping. daddiodanger nailed it.... too much rear roll stiffness can be a real handful on the street!!!!