I too want a more challenging USER passing game. I think a lot of it comes down to the types of plays you call. I use the Jets so I run a West coast offense and all of the routes are quite easy to complete. I try not to overdo it on slants and curls but I mean thats what they run in real life.. I don't think there are any sliders that will ever make it that hard because the CPU calls lots of zone defenses.
As for your penalties, I wanted to ask why you choose to raise DPI and lower OPI? If the purpose is to make the game more challenging that is reversed from everything I read. I haven't tested it in depth but this is from M13's penalty talk and is the logic I am going by, from KBLover in the Penalty thread:
"Defensive Pass Interference
Higher: Decreases the aggressiveness of the pass coverage. Think of it as the defender is worried about triggering a DPI call, so he plays back more and more conservatively. This is probably why we don't see more DPI with it up high.
Lower: Increases the aggressiveness of the pass coverage. The defender isn't worried about the penalty call and is going to make the most aggressive play he can. While this sounds like it always favors the defense, it can burn the defense if the defender is aggressive and/or has low AWR/PRC/MCV/ZCV.
Interesting thing here is that I think lower DPI is overall more help. Defenders tend not to have a lot of ball awareness - until an interception is "rolled up" (you can almost see it, the defender will take coverage/route to the ball with a different animation, etc). This doesn't create more of that animation (INT slider), but it lets more "free form" aggression to play out i.e. "I see the ball and I'm gonna swat it/pick it/attack that pass." I think lower plays out both the "Plays the Ball" trait and the AWR/PRC/MCV/ZCV of the defender better.
Offensive Pass Interference
Higher: The receivers run their routes more passively. Similar logic as above for DPI - the player is concerned about triggering OPI so there's "physicality" in the route running. This might also impact press coverage as well. If the WR are less physical in their routes and ball reactions, it would follow that press should last longer. Higher tends to emphasize "those who can" i.e. the guys who can run sharp routes, beat press coverage, make the special catch, hold on in traffic.
Lower: The receivers run their routes with aggression and physically. They worry less about OPI calls and will do what it takes to get the ball. They are more willing to play like Michael Irvin or other physical WRs. It follows that they'll also tend to go aggressively after passes and may beat press coverage more."