I hesitated for a long time, wish I hadn't...
I had my 2016 GLS auto remapped the other day. It has 108 ks on it now after nearly 4 years, so not a high mileage unit. But I've added so much junk in the form of a canopy, fridges, second spare, tools, camping junk etc etc, that it was getting heavy. I had a major service at 105 ks (has actually been serviced every 10 ks since about 40'ish) and asked for the intake manifold off and cleaned. Trusted mechanic said it was only cleaned because he had it off anyway. Otherwise, really didn't need it. And no, I've never had a catch can on it. But I had been feeling for a fair while now that it was getting sluggish. So I was actually hoping it was gunked up and I would magically get all my (perceived) power back after the service. But nope, no improvement at all. So, I pulled the pin and got the remap done.
I did a lot of homework. Chips vs remap vs chips vs remap vs....on and on and everywhere I looked, I could find good and bad reasons for both. In the end, I went the remap for $1300. Instead of $1500 for the cheapest chip option I thought I could trust (DP Chip) One of the main reasons was because I could try the remap for 7 days and if I didn't like it, they would put it back to standard and refund every single dollar.
I asked for a mild'ish tune. All sorts of outrageous claims are made about getting a billion Nm out of these little diesels but I made it clear that I just wanted some more low down torque for towing and offroading. In the end, I got a claimed 443 Nm at the wheels. I think this would equate to around 570 at the flywheel, correct me if I'm wrong. NOTE; NOT dyno'd, just a number from the tuning software. To be clear, I don't really care about the exact number, just the noticeable feel.
It's now a different car. By no means a rocket ship, but so much more driveable. The main thing I've found is that the torque converter will lock up a lot earlier and stay locked a lot longer. I live in the hills east of Perth and I have always been annoyed about how easily the TC would unlock, go slushy, and waste fuel and generate heat. Now I can drive up a particular hill in 4th, TC locked, at 60 kph, with a light throttle whereas before I usually went back to 3rd to try and ease the engine load and keep the transmission cooler. I have a Scanguage giving me trans temps and the difference now when I get to the top is around 20 degrees cooler. Every single time.
I can now accelerate up Greenmount Hill ( which I think is in places around a 1 in 11 - 12 gradient ?) in 4th, with a pleasurable surge of power and without the TC unlocking. I can also get to 80 kph around a 100m earlier on the same hill when leaving a particular intersection. And if I just leave it in drive around town, it changes up earlier and is just a whole lot nicer to drive.
In the short time I've had the remap, I can't say I've seen any noticeable improvement in mileage, but maybe once I stop putting my foot down for the the fun of it and drive like a more...ahem.. mature person, I reckon I might see around a 10 to 15% improvement there. Thats just guesswork from the trip computer at this point, but I'll report back later.
Anyhoo, from my perspective only, if you have been thinking about it, just do it. Do your research and make sure you're comfortable with whoever is doing it. Try and avoid cowboys. Ask a lot of questions. Make sure you feel comfortable with the people who will recode your cars brain, basically. And, you can always go back to stock standard.