I agree with routy. Test for leaks using your hand or a candle to feel around the joints. fix those issues first.
then, once you get to jetting... i went to Niche Cycle (
http://www.nichecycle.com/Items.aspx?code=MIKUNIJETS&key=cat)
reasonably priced, good selection.
as a side note, you only need to visit that dealer once more, to punch him square in the mouth, since, as you can see, they clearly make jets for this bike.
read serowbot's carb tuning post (you can find it through the table of contents in the tech section) and jet that way. someone else's jetting with a jardine won't necessarily be the same as yours, so tune it to your bike, not just your exhaust.