Keep in mind that its fuel that generates power. More fuel ~ more power ~ more heat.
Some of that heat will appear as an increased EGT. How much depends on a number of factors.
The moment that the module de-fuels it no longer meets its advertiersed power levels
Increased air flow will assist maintaining EGT's. This can be achieved thru;
1. increased boost at that load setting
2. improved exhaust flow
3. improved induction tract
4. NOS
5. water vapour
The easiest (and least determental) are #2 & #3. Be aware that foam type filters are not TD friendly! Also consider fresh clean air. This can be an issue with a 4x4 if its used off road (some times you will also be presented with dirty water + air). Ensure the air intake is well clear of water levels likely to be encountered (this probably means fitting a snorkel).
Increased boost may not be possible at all engine load points. VG turbos (and controler ECU) are very boost increases. Dont think you will get away with a lot in this area without precautions, otherwise expect some wide fluctuations in boost (up to 10PSI) and corresponding ECU codes.
Ideally the module should be adjustable, either via manual control or via software, to suit your specific vehicle configuration. The one I have fitted its, and only took a few minutes to install.
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DaveO
ENG-TEK Diesel Performance Centre
Australia