[Ward]

If you previously had a slip on and then later addeed a factory pro jet kit will the sound of the bike change any?

 

[GreenEnvy]

Not unless the bike was not running properly before.
If the bike was running too lean or too rich you might notice a little difference once its jetted properly, but its not going to be very noticable at all.

 

[dj dunzie]

It doesn't change the exhaust note if that's what you're getting at. Might make the engine sound better if the mix is currently off, but more importantly it will RUN and perform better.