Jeremy, its not kero but it sure runs nice. I bought the Merlin new from Todd about 3 years ago. At first Todd was not servicing the engines and it had to back to Gaspar at Jetsmunt. This took alot of time going back and forth (weeks). I know I sent it twice for the same problem. The issue I GUESS was that the turbine would function fine on the test stand at Jetsmunt. After many cycles, the plug was enduring well. So they sent it back. The problem is when the turbine is in the plane and is being flown at 3/4-full throttle for 10 minutes. After a couple of flights (2-5), the plug would melt. I think that the plug location on the turbine was incorrect and it was getting charred OR the combustion chamber was not designed to protect the plug form extreme heat in the early versions. Anyways, other than burning plugs, the turbine ran great so i flew the lightning sporadically and just accepted it the way it was. I never pressed Todd about it. I was lucky to have other jets to fly. In October, at Jets Over the Cape, I took my lightning and Eric happened to be there and experienced my dilema. I changed the plug 2 or 3 times that day. He was very professional about the whole thing. He made a phone call to make sure they could do the upgrade and 10 days later I got my turbine back and its KICK *****! It was a seamless transaction.