The sway bar keeps the sled flat when cornering on hardpack.
I have treid a couple of sleds without the sway bar.....If you trail ride you will NOT like it and prob crash as the cornering gets really sloppy. It allows the front suspension to be totally independant which is very compliant and cushy and you can really haul the sled over on it's side in the powder. The suspension becomes much softer because the two shocks shair each others spring and valving when connected by the sway bar and the factory setup accounts for this.
You have to drill out the rivets holding the sway bar bushing in the bulkhead to re and re it......you might be able to reuse them once but they usually crack and or the rivet holes get %#!*%$ up....just be aware if you decide to experiment with it on and off...they are not overly expensive but around $40?
I am actually looking to put a stiffer sway bar on my PROX as I mostly ride hardpack trails and the oem 1/2 in sway bar is too wimpy and the sleds rolls too much for my liking.
ACE....I don't think you can use the EDGE sway bar as it is not the same shape/size as the PROX. Polaris lists a 9/16 and 5/8 sway bar as part # but they are listed as discontinued..I will post what I come up with for a sway bar and the results when it snows!!
You can also use a stiffer spring on your front shocks to keep it a little more stable without the sway bar.