How loose are the conditions you are going to be running on outdoors?

Reason I ask, you may find benefit to picking up the M2C rear toe in brace now and setting it to 3.5 degrees. This will plant the rear end much better on loose conditions.

As for the 30K versus 20K argument, a lot of it will depend on what you see at the track for how much steering you want. A large 1/8 track that just flows will benefit more for the 30K settting versus one where you have a lot of turns, quick changes of direction, etc. This will tie in to how your driving style is as well and what feels comfortable to you.

Good luck!