It's worth noting that, regardless of pop filters, some mics are inherently less prone to plosives (such as popping P's) than other mics. You might want to try a different mic. For example, a well-designed mic intended for hand-held vocal use, such as the good ol' SM58, typically does not pop.
Another factor is proximity effect -- where the bass frequencies get much heavier the closer you get to a mic. If you're hearing popping P's, chances are the orator is standing very close to the mic, which will also cause proximity effect. Here you get to kill two birds with one stone: engage the high-pass filter and turn down the low frequencies (even as high as 250 Hz) until the voice sounds natural, not boomy. Doing so will also reduce the amount of pop in the P's.
Finally, when a P is popped, it is possible that it is clipping a gain stage somewhere in your equipment, and some equipment does not clip gracefully. The end result might be added weirdness to the pop. The fix -- after first addressing the problem at the microphone -- is to optimize your gain structure.
