Assuming you have an aftermarket exhaust on the bike, you really want to do both - increase the airflow by either 1) pulling the snorkle out and putting in a single Uni or K&N filter (easiest & cheapest option) or 2) cut up the airbox and put pod filters on (this will flow more air but more work is involved).
Once you figure out the intake setup, you can either get the dynojet kit which contains larger jets, needles, etc, or just keep reading this forum and order the parts individually which will cost less.
If you have a pipe and go with a single Uni filter and pull the snorkle, you might try a 125 main (130 if its a really free flowing pipe) and a TBS neeedle. The cost would be about $25 for the Uni filter, $7 for the main jet and $15 or so for the needles.
If you go with pod filters, consider a larger main jet and a 45 pilot jet. If you go with the 45 pilot, you may not need the TBS needles.
There are a lot of great resources on this site which will provide you with the technical details of our carbs. Someone will post some links.
