[wtm442]

1) Do a tune up NOW. Plugs, cap and rotor.
2) Fill up the tank with premium.
3) Bring your vacuum gauge, timing light and carb parts with you (jets, cams, squirters).

Call the shop before hand and ask if they will provide what you are looking for - a dyno tune, and not just 3 pulls.

I would never make more than one change between pulls. If you make 2 or 3 changes (jets and timing, for example) and the HP does not change, it could be a big gain with one of the changes and an equal big loss with the other change.