There is a lot of stuff here and elsewhere about how C ratings are largely BS and marketing. There are also threads here and there where guys actually test batteries and try to determine the "real" C. But there is no real definition for C. Look at it like this. If you got a 50C 5000mAh battery, that would suggest 5*50 amps=250amps. So that should be plenty. I am seeing more and more batteries with claimed C's of 100. You should always check the size and weight. Higher C batteries are usually bigger and heavier so they may not fit in you battery area and you are carrying around extra weight. If you are just bashing, then very high C batteries are probably not worth the extra cost.

A higher C battery should have a lower IR. If it actually does, less energy will be be left in the battery as heat. If your battery just feels slightly warm after a run, you are OK. If it feels hot like the motor, you need a better battery.

Hard core racers may get slightly more power delivered over a race because less voltage is dropped across the battery resistance but they still have to carry the extra weight. Others can say if they actually get better lap times with one battery over another.

Bottom line, 40 or 50C should be fine.

I am using this battery in my 8ight E 4.0
https://www.genstattu.com/gens-ace-5...eans-plug.html except I changed the connector to EC5.

We play race on a dirt track. A bunch of guys have 6S RTR Talions and they run out way before me. I have the 1900kv motor, 14T pinion, 45T spur, and the XR8 Plus ESC. The battery is just slightly warm after a full run. No clue if that would win races but it is more speed than I can handle.