Going Boosted!!!!!!! :D

[cali yaris]

stock Yaris is approx. 106 bhp, and 90-95 whp.

Looking forward to seeing the other, more complete dyno charts.
Sorry for your tuning troubles, it's not uncommon.

Australia's weather is really hot and humid with air intake temperatures at 40degrees and higher on hot days not very good for turbos ...

Yes and no. Higher temps, yes. Although I've raced in 100 degree heat and the car felt pretty strong. It's all about intake temps (see below).

Even at those temps (humidity will raise your power not lower it, turbo motors love a little water) -- you should be making 150+ whp at 8 psi, at the very minimum.

Now ask them what your intake temperatures were on the pulls. Another critical piece of information any tuner would know.

Sorry, I'm trying to do this piece by piece.
These are all questions you should ask in the meeting with the tuner before you drop off your car. IMO.
Something like the following.

It may sound tedious and anal, but this will save you guys 99% of what I call "Tuning Grief".

Pre-Dyno questions:

Do you charge by the job or by the hour for tuning?
Which tuner from your staff will be running my session?
What data do you monitor, and will be able to report to me during and after the session?
Do you do partial pulls at constant rpm for drivability tuning?
How many cars like mine have you tuned before?
How many times have you tuned with the management I have?
What is your policy if something needs tweaking, repair or replacement during the session?
What do you consider too lean/too rich for my tune?
I have an idea what my car should make when you tune it. What happens if we don't meet that goal?
When was your dyno last calibrated?
May I see some before/after dyno charts from previous tunes?
May I contact 2 or 3 of your customers to get reviews?
May I observe another customer's session first?

And so on... until you feel comfortable you are going to get what you are paying for.