As far as i know the oldest P90's had nickel-silver baseplates later they started using chome and brass baseplates. I remember reading something about sonic transparency and that nickel-silver plating was the preferred way to go. Using more sonically transparent baseplates would prevent high-end loss.
Then there is another thing i seem to remember is a story about brass baseplates being used when dogears needed to be custom fitted etc.
But anyway, something in this direction i suppose, im pretty sure the nickel-silver plate would definately be the way to go with a P90, and appearantly so does BKP 8) .
