Thats not to say that it's impossible.....IF you have more mods such as a 330 kit. But only a piped 250x wont keep up.
As for comparing a banshee's 350ccs to a raptors 660.....You cant compare the two because one is a two stroke and the other is a four. Th4y are two different breeds of quad. You can't compare the cc's because the motors aren't anywhere near the same. BUT you can compare something like a 300ex's ccs vs. a 400ex's ccs. That 120 cc difference does make a difference. Just take a look at what a bigger (only 50 cc's more) 330 kit does for the 300ex. So cc's do matter, but it's not the only thing that counts.