I have recently installed the Donaldson Power Core Air filtration unit for the Toyota 200 series V8 Diesel. I have not had it too long but I think given a 12 month period I am confident in seeing improved fuel economy over that time. I can already tell the engine breathes ( intake side) a bit easier.

The kit it comes in from PDP has everything you need to install it yourself. It was easy for me but I have a mechanical mind and skills but I think anyone who just follows the instructions will have no problems fitting it. It seems well made and and well thought out.

It's not cheap by any stretch but you must consider any upgrade to an item that improves things and is well designed will return to you in time by a good service life.
You only get what you pay for is something we have all heard. That is not always true in my opinion, but in this instance I was willing to spend the money on this product for two main reasons:
1) peace of mind that my air is clean going into my turbos and engine,
2) Longevity in service life of the element itself.

Who should buy one? I think it depends on what you want from your 4wd. If you are only an occasional dirt road explorer but 99% of the time your on bitumen around the city and you service your vehicle regularly, probably dont bother.
If you are a serious traveller doing lots of miles whether towing a van or boat to distant holiday spots, or a daily dirt road traveller like many country roads offer, then probably yes, get one.
However, at the end of the day, buy what you think is best for you and your expectations. At least research the product and then consider it. The product is well made and does an excellent job as it claims. the rest is up to you.

As always easy and quick purchase love dealing with you guys

Good quality and team assisted with my queries