Cap size

I recently posted a question regarding cap sizes. It either did not get 
through or was ignored, probably the later. But just in case, I'll ask it 

I have a 6" coil with a 120ma 15kv neon. The best cap size for this setup 
is 0.02 ufd. I have 4 homemade poly caps run in series/parallel that give 
me a total of 0.01ufd. I'm running a balanced Tesla tank. Would the 
performance be much less considering I'm only using half the recommended 
capacitance? I'm currently getting 4 - 5 feet of spark. 

Tesla experimented with terminal heights. Does anyone know how much the 
frequency drops per foot raised etc?