NPP gives faster gains, drier gains, and is less slikely to cause sexual dysfunction than Deca, but the one downside is that it costs more, per mg.
NPP's reduced side are due to its shorter ester, giving the Nandrolone molecule less time to undergo enzymatic conversion , as well as less time to interact with the progesterone receptor. I have now spoken with several guys who all have major problems with Deca, but none with NPP, even when running 400-500 mg/week. NPP has become one of my very favorite steroids. It is a great nmass-builder with minimal side effects...can't ask for more than that.