The full monty requires just a race can NOT a full system. The full monty also requires a bmc or k&n air filter. The differences between both types of ivans kit are that the full monty requires modification of the air box/ carb rubbers and a different carb kit to the slip on kit(i think!
) The slip on kit requires the original air filter,as it would run lean with a k&n, but a race can or one that lets the bike breathe better than the original is probably required. Get the full monty if you can, as i have two fazers, one has the slip on kit and the other has the full monty. I don't really notice any difference in fuel consumption between the kits. It's really how hard you ride them
Hope this helps... Mike will be along shortly to correct me in case i've cocked anything up!