I tore apart many 603 filters last year on my own. I use an OE in mine, guess why.
The 603 and 617 use different filters, apples and oranges you cannot compare them. 617 filters come from more sources.
Just an FYI, the STP filter for the 603 is actualy a Mann, and the quality is decent. The Fram is different from all of them, and uses string insted of cotten. Its not a bad choice, but I did notice a slight drop in oil pressure, maybe it was just me.
With the 603 you have three choices:
The OE filter which is pretty good.
Every other brand, Wix, Mann, Hegnst, Car Quest, STP, whatever are all about the same. IE same source with a different box or label. In the case of the STP and Car Quest they don't try to hide this.
And Fram which kind of does there own thing.