Jumped from 2014 xm 154 to 2015 T3 174. There is a big difference. It sidehills easier and the rear end does not wash out as easy. Its about 1 inch taller, and it makes the sled easier to ride. I installed a post forward kit because i think its easier to sidehill the realy steep sides, you get more leverage when you do the wrong foot forward. Tried the dynamoe joe clutch kit i used on the 14,but it didnt work. The clutch setup is different on the 174, more accelleration at the bottom rpm. I like the T3 alot better than my 14 summit 154,and you do notice the difference if you ride technical sidehills etc. Even without the post forward kit. Not all riders like the post fwd,thats more a personal preference. The biggest issue with ski doo these days are the shocks, thats an expencive upgrade. I will try revalving them and maybe put on stiffers springs in the front.