Ok what is going to get some of the best performance here, the I.R.S. or the solid axle and if there are upgrades for each what is a good combination. I have a 450 Grizzly with the independent suspension and wonder if there are after market ad-ons that will allow me to carry the extra weight as I think the solid axle older brother has some advantages built in for carrying capacity. What about the comfort factor... Thanks for your input.