Gotta be careful with sway bars. Too much on one end or the other can radically upset your over/under steer condition. Too big a bar can all of a sudden mean you go into too much oversteer up front and promote rear end break away in a corner when you least expect it. Or vice versa. Go into a corner hot, turn in and here comes the rear end fast!
Best to experiment in a nice open paved area to see what you have before changing to bigger, not necessarily better.