When I was trying to help a fellow member of the Mutants and Masterminds community, I discovered a bug in the way that Ground Speed is calculated. It appears that it only uses the character's size into consideration, which is fine in most cases but it is totally independent of the Speed power. It also precludes having a Power Flaw that reduces a character's movement rate while it is in use.
The Speed power description states "You can move faster than normal. You have a ground speed rank equal to your effect rank. This also improves all forms of movement based on ground speed." The bold and italicized sentence implies that it will augment it, but the reality of how that power is set up it only generates its own, independent, movement rate.
There needs to be a central, common Basic Speed value that is modified by Size, and can then be modified by Speed and potentially other factors (like a Power Extra or Flaw).
In the current state that is impossible. A character that might be very small gets an impressive boost from the Speed power as it totally negates that character's penalties (where it should just increase the value, eventually negating it with a high enough power level). Additionally a character with Growth of significant value actually gets SLOWER with a single level of Speed.
Ah, but hopefully, now that we're re-raising them... 
