Hi. Thanks for using JA! I will try and help you out.
Yes, your readings are normal. Assuming your gauge is registering in HG. You are going to have some restriction on the system as the filters are doing their job.
Is your engine having some problems?
Thanks for the information.
The max allowed for maximum performance is 10.
Are you using a Cat Primary fuel filter?
The(NNN) NNN-NNNNhas a 10 micron rating. The 1R0749 has a 2 micron rating. These micron ratings are low in an effort to keep dirt and debris from harming your fuel injectors. I believe that your restriction gauge (if it's like the ones I have seen) was designed for Primary and Secondary filters with a higher micron rating (12 and 25). With a higher rating, the readings would be lower.
Thanks. You do the same.
Please let me know if you need any more help.