Add the 122lbs of this kit and there is only a difference of 314lbs. That's considerable if you are taking your car to the track, but for most of us who don't it is roughly the difference between driving by yourself and driving with two friends. I'm sure Mazda also had that in mind. Plus the 274HP that the MS6 puts out (which would be equivalent to what an AWD MS3 woudl put out) is not enough to compete with the EVO or WRX so Mazda simply tackled the 2WD market successfully instead of falling short of the goal in the AWD market.