I compiled a the basic information which sparked such interest in achieving better fuel filtration.

It is mainly CAT research as interpreted by George Morrison and others.

I hope this helps separate the wheat from the chaff:

George Morrison

The Mother of Fuel Filtration Threads

The information I am sharing with respect to injector and pump wear is the result of a many hundred thousand dollar study funded by CAT relating to injector life, or lack thereof. In this very thorough injector wear study, it was determined that the 5 to 10 micron particle size content bears a direct relatonship to wear rates. The reduction in sulphur content had minimal measurable relationship to wear rates when compared with dirt/particle counts.

This is a rather long story but the short of it is that our fuel systems are basically hydraulic systems. 20 some odd years ago hydraulic system manufacturers found that fine particle contamination is what was destroying/reducing pump and servo valve life. They established a system of 'cleanliness codes'. For our fuel system pressure and componentry, we should be achieving a minimum of a 15/13/10 ISO cleanliness. For a garbage truck hydraulic system to live, it needs a minimum 18/16/14. The higher the number the more allowable particles in the size range of 2, 5 and 15 microns. Most diesel fuels from the pump are in the region of a 20/18/16 or even as high as 24/22/19... Not even fit for a 1,000 psi hydraulic system in a garbage truck much less a 30,000 psi fuel system!
Thus, if we have a fuel filter which is only 50% efficient in removing the 5 to 10 micron particle size, fuel injector and pump life is going to be short. The fuel system/injectors will no doubt make it through the warranty period but take a look at the posts on this site and the 6.5TD and you will notice a trend.

Dirty fuel was almost acceptable with the old mechanical, 3,000 psi injectors but with our high pressure, high precision injection, contaminants mean drastically shortened life.
In the next weeks we will know exactly how efficient our fuel filter is on the Duramax.
George Morrison, STLE CLS

Regarding a 'real world'fix. One of the fellows on the 6.5 site portion ran a 'before and after' on a Racor "S" series and it was indeed a 2 micron 98% efficient filter, very similar in performance to the new CAT high performance 2 micron absolute filters. Our OEM Duramax is 'supposedly' the same filter medium, same performance level. This is what does NOT make sense with our first test..
If the OEM filter does not meet the 2 micron absolute performance level, we will source one that will!

It is absolutely imperative that we have a filter capable of 2 micron 98% efficiency as we need to minimze the 5 to 10 micron component. This is the particle size that creates high wear in our pump and injectors.

The fuel analysis that we are doing actually counts and calculates the number of particles per gallon for each size range from 2 microns to 5 microns to 15 microns, very accurately.
Plus it computes the amount of water being carried in the fuel in parts per million, so one knows exactly how much water is present, not a vague percentage.
George Morrison, STLE CLS
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George Morison

In talking with a Racor engineer last week, our Bosch pump is consertavitely rated 60 inches! Our current OEM filter draws less than 8 inches, so an additional filter is no problem; in fact GM is currently working on a primary to put in between the present filter and the tank. What do you think that is telling us

It can therefore easily handle a both a primary and secondary fuel filter, especially if one or both are synthetic or microglass media. Moreover, if it is 'clean' fuel that the pump is processing, THAT is the key to both pump and injector life. i.e. if the pump has twice the load, if the fuel is ultra-clean, the increased load is much better than processing dirty fuel at half the load..
George Morrison, STLE CLS
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Goerge Morrison

How I wish we could post photos on this site! I have some incredible scanning electron micriscope photos of failed injectors at 95,000 miles; totally, completely destroyed. Due to dirt. Current diesel fuel regulations are for 1980 3,000 psi diesel fuel systems in which injector replacements were $28 each. Our current 30,000 psi fuel systems require ultra clean fuel to live. To meet current federal #2 diesel fuel standards, diesel fuel is only filtered to 30 microns when it leaves the refinery. The 7 micron particle is the Duramax fuel system killer. This is why CAT switched from a 20 micron nominal to a 2 micron absolute fuel filter for its Hueiu engines 2 years ago. Their fuel pumps and injectors were not lasting through warranty and the replacement costs were costing CAT millions of dollars until CAT switched to the new ultra fine filtration medium.
Continued....
George Morrison, STLE CLS
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roegs

Here are a couple of quotes from George (Morrison) from an earlier Fuel Test Results thread. It implies that CAT does make their own filters...

"Fuel filters are constructed by human beings (except for the CAT fuel/oil filters which are totally robotically manufactured and incredibly flawless)"

"If only we could get CAT to expand its filter line we would have that filtration level.. But, CAT recognized the lack of quality fuel filtration and had to go out and build a factory to make filters capable of achieving the level of quality/filtration needed for maximum fuel system life."
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56Nomad

I was looking for the location of the CAT filter plant and came across some interesting sites about CAT filters, even though they're in-house sites:
CAT Filter Construction Literature
CAT Filter Features & Stats

CAT High Pressure Injection System Drawing & Explanation
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HB

Injector Wear Testing Description Wear Index Test Description

Wear Index Testing

Wear Indexing was developed by an industry consortium to provide more meaningful and credible test results. The Wear Index number is based upon a correlation between physical damage observed on high pressure fuel injectors and the amounts of 5, 10 and 15 micron particles measured in the filtered fuel. A higher number indicates more wear and damage to fuel system components.

To determine the Wear Index shown below, a Cat 3406E Engine was driven by a dynamometer, while low sulfer diesel fuel, vibration, fuel flow and temperature closely simulated real world conditions.

Bottom line conclusions.
Four competitive fuel filter brands and the Cat 1R-0749 High Efficiency Fuel Filter were tested to determine Wear Index. As illustrated by the graph below, the Cat 1R-0749 outperformed all four competitors by a significant margin, indicating that it provides superior protection against destructive particles. As the graph below indicates, the next best filter, the Fleetguard FF5319, may cause fuel injector life to be reduced by up to 50%.

The others would rapidly lower life even more significantly. Fuel consumption and emissions would also increase. The cost of these increases would quickly exceed any price premium paid for the Cat High Efficiency Fuel Filter.

Wear Index
. Real world vibration
. Test fluid is low sulfur diesel fuel
. Constant 170