Reflectix is a radiant barrier which is commonly used in the backpacking community in cozys, such as by www.antigravitygear.com
Our discussion started with lids for cups and other pots; the jetboil is already insulated, and might not benefit much by reflectix. With all due respect to Roger, yes, do read the reviews on the jetboil. It has all the limitations of a canister stove naturally, but there are reasons it is a popular stove among the lightweight crowd (not the UL crowd?) I have a jetboil, and every guy I've hiked with lately wants one as well after seeing it in operation. I can have a hot drinks for 4 people three minutes after taking it out of my pack; while holding it in my hand if necessary at a rest stop. As Roger mentioned, it is 'low power', lower BTU output than other stoves. That is by design. It is a tradeoff of speed and fuel consumption. There is no reason to pump out more BTUs than the flux ring can absorb. I think they dialed in the BTUs well, since I can literally hold the metal ring below the neoprene while the stove is running.