MMC caps?

I found a good source of .0062uf 2kvdc caps for a good price. I used 5
strings of 6 with a 9kv 30ma neon and got 12" arcs out of my 3" tc. I would
think I am over powering them, but they don't even get warm on long runs.
Would it be particle to use these for a larger coil? Also, I can get great
number of them (1000's) cheap.