Boo,
Go the music store and pick up a wind screen and that should solve your "P" and "S" problems.
I also used an SM-58 for a while and yes, it's a good mic, but I always felt it lacked the high end response. It has a great mid range and low end response, and that may be why it does not amplify the "P" and "S" sounds as much as the Sennheiser E-855.
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)