Not really. Everyone on here says that OEM is best and i agree in some aspects. But I have NWP aftermarket in a few of my saws and they don't seem any lower in power. I can get my 044 with a big bore to run with 046's stock.
Not at all, but some aftermarket parts are poor quality. Ask about the parts you need and get reports from other members here about what brands of am parts are decent.