Im looking to get a 6s lipo for speed runs and im wondering would a high mAh and C rating help me with top em

mAh=milliamp-hours, which is how long the battery will last

C rating is how fast the battery will discharge.

If you're doing only speed runs then the more important number is the C rating. However as you get to better batteries the mAh and C ratings will both go up.

You may want to consider quality too. A cheap battery with a high c rate and mAh may do what you want, but not last as long as a better battery.

"c" ratings are arbitrary numbers created by each manufacturer. There is no standard on how to arrive at that number so most manufacturers basically create their own.

Think of it like a tank of water how much the tank can hold is your mah, then there's hose connected to it, the bigger the c rating the more water will shoot it. And I wouldn't say cheaper batteries are less quality.. My reedy 2s lipos are 4100 mah and 65c I think and are like 80$ and the turnigy nano techs have more mah and discarge rate and and are cheaper and have lasted way longer

Ok how many amps does the motor draw. The battery should supply atleast 50amps more for speed runs. Equation to determine battery amps is
Mah/1000x C rating=amps

Good analogy.

The NanoTechs have lasted longer because they are a much higher quality battery, the reason they are cheaper is because they don't go through a series of wholesalers, distributors and retailers who all put on a margin. Hobby King products such as NanoTechs go factory - warehouse - you, no middle men taking their 50%.

All good points here.
My .02 in a nutshell: The "C" rating will affect how "punchy" a battery is, and while other factors do apply, in general your top speed is more a result of the voltage of your pack.
It's also true that C ratings are very subjective to who they are coming from. C ratings are OK for grading packs between the same manufacturer, but as stated by another member the C rating in general is a gray area at best.