Look up a guy called "ezblast" on buelletinboard.com. He is on here also but seems to spend more time on that forum. He is THE blast guru. There is a wealth of knowledge on this board but it is mostly XB related. Ezblast can tell you everything you would ever want to know about the blast. He has steered me in the right direction more than once concerning my wifes blast. There is a 600cc kit for the blast but not sure how pricey it is. Here is a pic of ezblast's blasts.
P.S. If you by chance need a low seat for you blast I have on for cheap.