so i have been getting pretty serious about riding and i wanted to make some upgrades. looking over BF, i saw many people have recommended new wheelsets, engine, power. well right now i think a power meter would be best to improve my abilities. a new wheel set would be nice but i doubt ill notice a difference in speed or any other qualities, seeing that i am only 140 lbs.

so what are my options of going about getting a power meter? new crank? new hub? which brands?

also whats a good stem? thats a must.