two weekends ago i finally got my order for larger sway bars for my mazda6. the front requires some work to install but the rear is very easy.
according to the mazda6 forum, the larger rear bar is all that needs to be done to make the car handle well for autocross and if i had done the front before the rear, i would regret it.
so i did the rear one day after work, really quickly, and still have to do the front since i was holding on the h&r race springs to show up.
the difference is amazing. just like when i put a rear bar on my 79 bmw 320i (which came with no stock rear bar). its a totally different car now, the mazda6. it had a small rear bar and the new bar i put on is huge so now the car feels dead flat through the turns and driving on the highway. no more sway from the 25-30mph cross winds were always have here.
i don't know how doing the front first would have affected the car but if i could have easily put it on, i would have done it at the same time, but just the rear makes me totally understand why some of those guys only bought rear bars.
here is from the site on the mazda6 bars.
Bar Sizes
Stock - 23mm Front, 19mm Rear
Racing Beat - 28.5mm (1.125") Front, 27mm (1.0625") Rear (Both bars feature solid tubing)