Boost Guage

It all depends on what you are driving.
If it's a 3lt Patrol then they sometimes have a habit of over boosting if the Maf sensor gets dirty and can cause extensive damage to the engine.
Cheers Dave

If your vehicle is stock i would not worry about EGT or boost gauges, unless you are doing some heavy towing. If you have played with the fuelling or adjusted boost, or plan to do these things later on, then yes you should fit both of these gauges. Some people also just like to know what is happening under the bonnet.

A boost guage can also let you know if you have a hole in the intercooler or a loose hose clamp. (drop in boost) It is better set up with a pyro as the first sign of a boost leak would be higher EGT. For peace of mind I would get both.

If you have a stock vehicle and otherwise are not too interested in the readings, then extra guages are of little benefit. But if you have a GU 3.0TD or have done any mods to your vehicle, then aftermarket gauges can help. IMHO the EGT guage would be the most useful, the turbo boost is not that critical (usually!).

If you have a post-2006 vehicle, then they have a common OBDC port and you can tap into this with a range of aftermarket devices.

On my 200 cruiser, I have the scanguageII and can see a huge amount of things ie. boost pressure, intercooler temp, water temp (accurate, unlike vehicle guage), auto trans temp, etc... and thats just for starters. For under ~$170, its the cheapest way to get a whole bunch of guages. The only guage I have added is the EGT, the 200 doesn't have one of those as part of the vehicle instruments.

One of the benefits of the auto transmission temp reading was seeing how hot the auto got under load. As the 200 has bulk power, often I would leave it in high range and use the power on tough 4WD sections. But after seeing how hot the auto got (~126C), I will now go to low range earlier and see a ~20C drop in auto temp for the same bit of track. Without a guage, the vehicle seemed to be handling it easy and I was none the wiser. But now I can look after the auto box a bit better.

Same concept goes for EGT temp, you can see when you are working the engine hard and have data to know if to back off, or go down a gear (higher revs for same load = lower EGT).

Cheers

Captain