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Piston jump boots

I dunno if you have ever seen this guys 'rocket boots' (not really rocket powered) but they are sort of neat. They do not get the same results as simple mechanical leaf spring sort of moon boots I see, but the concept is pretty interesting for those of us who are fans of combustibles. 

this is a video
http://www.youtube.com/watch?v=w7s-tnzPZ3c

article
http://www.technovelgy.com/ct/Science-Fiction-News-Comments.asp?NewsNum=740

Now my question: How would you improve this sort of unimpressive piston powered boot? I was thinking if one could double or even triple the chamber size of that piston, or use multiples of them, maybe use a more potent combustible than gasoline.