I hope you mean 6S A123 or NIMH cells? the quark isn't capable of 6S. I need to come across the first who uses 6S lipo packs in his truck with the Quark without killing it.
I use mine on 6s every once in a while and it works perfect so far. I usually keep the gearing the same as when it's on 5s, but it doesn't get much warmer. No caps, no internal mod, just the rcm heatsink with a 40mm novak fan.