Ki mechanics 101.
	Ki, is a concept. Ki is a form of energy that flows rapidly through all things in the universe. The Ki 'PL'(Powerlevel) of a fighter in DBZ is not just a number that can have a few zero's added on to make the fighter seem stronger. It is rather the result of mathmatics and applying a scale to a fighters general ability to influence the Ki flow around them. How so? I shall explain. Imagine Ki like a spider web. When something touches a spider web, the spider in the center feels it through vibrations obviously the stronger the thing that touches the web the stronger the vibrations telling the spider just what its run into. Ki in its flow through all things can be manipulated and these subtle changes in flow can be detected by those trained to be sensitive to it. All of the earth Z fighters had the ability to determine Powerlevel from these Ki flow vibrations however fighters not of earth like frieza were unable to. Thus the scouter was created, a device worn on the face which was sensitive to the Ki vibrations. Translating the ammount and strength of the vibrations to a number. (The 'PL' which is known today.) DBZ characters arnt the only people to use ki, a lot of martial arts fictions do including Ranma 1/2 and streetfighter. Though Ki flows through all things, not everything can use it. Things which are just naturaly engulfed in the Ki flow, like trees and wild animals dont make big vibrations. Infact their vibrations are so small that that they go unnoticed, like electronic scales, the 0 level can be set anywhere the operator chooses. Thus tree's and things like that are the zero line as they have next to no influence on the ki flow. Regular, untrained people have a very small influence on the ki flow, Aparently the average untrained human has a 'PL' of 5. This is probably due to the fact that the majority of humans do not even try to excert any pressure on the ki flow but live unnaturally.
With that said, how does a person get a higher PL? you may ask. Its simple. The more control, a creature places on the Ki flow the higher its PL will become. The more control a Technique puts on the flow, the higher PL it has. Of coarse controlling such a force isnt easy, its nearer to impossible. Whenever somebody applies pressure to the ki flow the drain some of their natural internal energy. Raw control in this method is fatal to the creature involved more often than not. How then do the Z fighters pull it off so regularly? Easy, controlled techniques. Notice that main characters dont normally just throw around energy without ending themselves where as other techniques such as the kamehame-ha technique causes far less drain. The act of holding back Ki then throwing it into a visible beam can be tiring, maintaining that beam through funneling more Ki into it can be worse. Becoming drained from the use of Ki can be just as bad as overusing Chi, leaving the fighter weak and near death if not dead already. So what? Well in the end the point is that Ki power is not a number but a scale. Your natural energy, multiplied by the strength of technique adding in how long you prepared for the attack AND how physically fit they are equals the resultant output. A Z fighter in a relaxed state will have a naturally low 'PL' as they arnt exherting their natural energy or their techniques. Some creatures place a constant clamp on the flow to keep themselves alive (Freeza is an example.) And so will have a relatively high 'PL' even when at rest. Somebody who knows nothing of Ki, yet is very fit and has a strong technique will still have a high 'PL' and that 'PL' doesnt necisarally translate to the ability to fire huge blasts of Ki vibrations at your enemy. Natural energy can be called stamina if you like. Another thing to keep in mind is that the visible aura on an aura using character is not the whole aura, merely the Ki control natural extending from the body into the visible spectrum and even beyond. It looks as if its blowing in some intangible breeeze because it is, as its just the internal energy of a fighter overlaying the ki flow. Often this only happens when the fighter induces it or is 'flared'.
	Remember too that most Ki attacks are slower than light, they emit light which reaches the target before it does. To speed up the Ki attack often concentration and preperation are needed. How do the numbers relate to the UC-RP scale? Well the scale used in DBZ was pretty massive, jumps of millions etc. This does not mean the same thing in the UC-RP scale. Remember that going SSJ can be a level 1 advanced skill. To work out the 'PL' on a UC-RP sheet remember that any ki skill (Or combination of skills like martial arts and Ki manipulation.) which is at level 5 would grant a PL of a million. (Yes, even ki knitting level five would grant this PL but what kind of freak knits their opponent into submission.) As ive said before the scale is a rather huge jump, and is not meant to represent normal people. When thinking UC-RP think comic-book over the top super-heros.
Ki & Powerlevels	Chi	Do-it-yourself Energy