don't plan on rac'n for a few weeks. Using a CFX Lipo charger to discharge to 3 volts, what charge is good to store at?

SMC recommends around 40% charge for long term storage. Through trial an error I have found discharging to 3.7V at .8C gets me right at 40%. (.8C for a 4000 would be 3.2A).

But for just a few weeks, you are probably fine.

after a 4 minute heat in the main, put the car away till next time.

I'm putting 1800 mah back into my 4000 mah pack after a run.

If you are the last main, run another 2-4 minutes, the racing will still be close and fun!