Hello. I've got both a filter top B&M FP gauge and an in-cabin Autometer FP gauge. They show different readings of 30 psi on the B&M and 25 psi for the Autometer. What might some of the causes be?

Also, if I'd have to choose one over another, which would likely be the more reliable reading?

Thanks.

A-dub

 

the one on the filter would probably be more accurate. i'm assuming the in cabin is an electric gauge?