If you like it as it is now and intend on keeping the car for a while, I'd leave it stage 2 personally.
Turbos lead you down the dark path of greed and corruption. Be happy with your Jedi power, take some death sticks, go home and rethink your life

In all seriousness, KO4s are tricky buggers to tune properly because of their spool characteristics overwhelming the engine's VE point at a specific rpm. An over cooked one feels worse to drive than a tried and tested Stage 1 tune.
Personally I don't feel Stage 2+ is as nice as the lower levels of tune. Too many caveats, but that's just my opinion. It's your car/hobby, so do what you want with it
Revo or APR tunes are very good, so you can't go wrong there.