^Some apps prefer one over another, which is why I posted what I did earlier in this thread.
These are AFTERMARKET filters designed for a LARGE variety of apps, there are 'bound' to be some apps like yours which don't 'like' certain filters due to a spec.
For instance, could the issue you had with the P1 be the bypass relief on the filter(differential pressure across the media) relative to the OE factory filter? I mean, classic is basically the same as P1 just different canister, media, relief valve spec, and adbv material, right?