With the Blast you are within your own relm, most leave them stock, as they out grow the bike within the first year and just feel they wasted the money.
Otherwise do what you wish, just use some common sense and begin to add and improve on what you want and need.
As far as mirrors just take off the stockers and go with a bar end mirror, then for the body I would clean it up by removing some of the body plastic. As far as performance upgrades I would assume since they are carburated you would need to use different jets, or needles on that for fuel addition and then a higher flowing filter would all work together with a new exhaust[up]
