Oodles of 1911 grips on Evilbay, some of the guys on the UBC have bought from a Thai seller that does interesting and reasonably priced grips.
Don't know about a silencer, I'm sure it's possible but it would take a bit of work and you would probably have to take it off every time you cocked it.
I shoot mine on 1/2 power to keep the neighbours happy, the difference in noise between 1/2 and full power is considerable.