Rebuild kits generally just have the stock jets....if they have jets.

Lancer sells jet kits in the Marketplace section, with a gasket and a selection of jets that will fit your carb.  You can then play around the jets and find the one that runs best.

DYNAJET sells jet kits - but generally they only have a single set of jets that they think will work.  And they don't really take into account where you live or any mods you might have done (plus the sizes they list are weird and don't match the Mikuni size numbering system).

You can order your own jets form JETSRUS if you know what you want.