if its like my blower, the carb is a 40mm Kehan and the hose connecting it to the blower can be found at any auto parts store. The fuel line should also be easily found at an auto parts store.
As far as what is the best carb. My understanding is that the one that was shipped with the kit has the best balance of power, fuel mileage, and fuel control. You can get more power from larger carbs though, but you sacrifice some things for the sake of that power. The mileage drops from about 25mpg down to 17-20mpg with larger carbs and they get a little harder to cruise with as I understand it. Your on and off the throttle more. Im going to try a 52mm S&S Super G on mine as soon as it gets here (next week I guess) I will post how it performs.
It would probably be a good idea before ya run that thing much to get someone to check the air/fuel ratio on the bike too. I havent heard much trouble from the blower bikes, but if you have it too lean etc you can cause some problems. Any good bike shop should be able to check that for ya.
A guy named Lamont
http://www.lamonster.com sells the blowers and is a very knowledgable guy about the mod. He might be of some help to you as well.
I hope that helps some.
