For my Gen3 21 I have replaced the polymer guide rod with a tungsten one with factory weight spring. I am too chickenshit to venture away from factory weight springs. I have also replaced the trigger connector with one from Lone Wolf (I think) in order to get a better feeling trigger, though I have considered replacing that one with one from Ghost. All these parts are inexpensive.

I am considering having the grip reduced and stippled like Gary mentioned. My only concern is compromising the durability of the frame.

Gary, have you heard of any frame related failures due to grip reduction?