I have a P01, and, frankly it's just about stock..I installed an extended firing pin, and spring, reduced power firing pin saftey block spring, reduced power trs, and a #15 hammer spring, everything else is stock.. I'm happy with it as it is, If you decide to swap hammers, you should do it before you get about 1000 rnds on the gun, otherwise you'll need to change the sear as well, this is what CGW told me, sear and hammer have to wear in together.