ECU re-mapping for the diesel Sorento is the most efficient and safest way to extract about 30-35% more power and torque from your engine. I had mine done to a 2005 version and it was supposed to be downloaded from the ECU and flashed back through the interface terminal below the steering column. It was done by a Korean Hyundai motorsports specialist who comes to Malaysia once a month. The re-mapping is a full "check sum" method which means it is invisible to any service centers diagnostic equipment...it just doesn't show up! So my warranty is not affected as nobody knows it has been done!
During the re-mapping the process was supposed to take a few minutes but the ECU would not re-flash in-situ so the chip had to be removed from the ECU and re-programmed on a separate connector. The re-mapping program was prepared by Hiyundai Motorsports and was all done through windows on a laptop. Very professional I thought.
The Bosch ECU's planted in Sorentos only have 2 maps apparently, one for cold climates and one for hot climates, (or so he told me) so tuning it for performance makes no difference to the "durability" of the engine. In fact it makes the engine operate more efficiently. The process is completely reversible.
I toyed around with the bolt on tuning boxes, but these things are rubbish I think, and just trick the ECU into believing the engine is running slower than it is, thereby squirting in more fuel. If anything is like to damage your engine, these tuning boxes will in my opinion. The ECU re-mapping still uses all of the sensors so it works as "original" including temperature sensors and engine cooling. It cost me about GBP350, and I had the Sorento dyno tested which revealed about 182 hp at the wheels at 3500rpm and torque of 435N, at 2800rpm, (after fitting K&N air filter).
So far I have covered 6000km with the remapping and the engine is very quiet and smooth with a huge kick in it at mid range overtaking speeds, it will easily and quickly reach highly illegal speeds and just keeps on accelerating up the long steep hill to my home.
I believe the 2007 diesel powered Sorento is using a VVT or something turbo with similar outputs.
If you can get this re-mapping done I would go for it. My FC has also improved, surprisingly from about 9km/l to 11km/l.