Recently purchasing a HPI MT2, I decided with the packed snow it was OK to run the truck through its break in procedure. I've run about 4 tanks through it now and would normally begin to start tuning for more power. I'm worried though with the 0 degree weather, is it better to keep the truck on factory "rich" settings versus leaning it out? Also, by leaving it rich will that do any harm in any way? You opinions are greatly appreciated.

Thanks!