Interesting. I've got a Quark 33amp and the C4 combo and I just toasted the Quark for a second time. The first time I got maybe 7 packs run through it before it burnt up. The second one was on the very first pack. I wonder if there is an issue with the C4 motors?
I sent my whole truck in to Quark (Sky & Technology actually) and they are going to disect it for me to see what the issue is. Their customer service has been great. I'll keep you updated.

i would recommend the quark 33a and the 8000 mamba that will get you over 35 mabey 40 with stick pack and 50+ with lipo

Or just get the Mamba combo, and you'll be still hitting those speeds. lol