All depends what you want your sled to do, if you like cat walking then leave it alone... If you wanna be able to climb then you gotta spend $ to make it right.
Just buy racers edge rear arm... Ice age 163 rails work good, u use the stock Polaris front arm and shock, this will make huge difference from the stock 155.
Boostit has a 13 pro 163 low boost kit running stock rear skid.... It wheelies and struggles in trenches made from other sleds. Pretty...
put areo charger kit on mine and didn't do vent kit....it runs strong ...i just make sure to clean snow off hood vents and headlight delete vent as much as possible...i also didnt want to cut my panels!!