I quit using Fram a long time ago after cutting a few of them open and seeing how cheaply made they are but...I've never cut open the HP filter. There are many sites on the web about filter studies and this is just one of them.
http://people.msoe.edu/~yoderw/oilfilterstudy/oilfilterstudy.html
Also, I like to use the largest filter that will fit on the car. The Fram unit would be the PH8A (what should be on yours) and you can cross reference that number for other brands. When I pick up a new filter like a Mobil 1 and it weighs twice as much or more as a Fram, it made me wonder so I cut them open...and yes, switching to synthetic can find leaks but that can happen in any engine. There are pros and cons to synthetics. One being expense but there's also a lot of info on the net about that too. It just boils down to how much research you want to do to find what's best that will suit your needs. Keep in mind that synthetics are still made from 'normal' base stocks but with a very different additives package....