Triton 4m40, turbo install maybe also intercooler

Always install an intercooler with a turbo if possible. The intercooler will cool the incoming charge and therefore make the incoming air charge more dense and therefore has more oxygen in the given amount which finally ends up in the cylinder.
This will create a slightly higher compression than no intercooler and provide ample air for a good as efficient burn as possible. Keeps the oil cleaner for longer too because less soot is created with the cleaner burn.

Don't get greedy and try to make it have lots of boost, just be happy with a moderate amount and the life of the engine won't be compromised.

On a hot day without the intercooler you might find hardly any turbo effect is noticeable because everything is hotter and the air will be less dense.
Because the turbo is a compressor and compressing raises the temp of the air, the compressed air will be less dense, so it is good to have the cooler to take away some of the heat of the air, the engine will like this.

Having an intercooler as well as the turbo may increase your fuel economy and actually use less fuel under some conditions. If you use the power all the time it will use more.
If you get the turbo make sure you use a well known worldwide brand of proven oil, eg, Mobil Delvac MX or similar, not Boutique oils or stuff recommended by Repco or Penrite. There are many people on various forums having oil related problems and there is popular oil starting with P which is a common factor in many of the problems. Use what a transport company uses not flashy trendy stuff if you value your engine.