My friend has one in his MP777. Good engine with the right pipe. He ran it with a Kyosho pipe and didn't like it so much. He then got the Sirio pipe and the engine woke up. Very crisp feeling on the low end. Get's on the pipe immediately and pulls all the way through the RPM range. I'm sure it'll work as well with other pipes but my friend thinks the Sirio pipe is specifically tuned for that engine...probably so. He runs the standard Kyosho clutch setup (al shoes, 1.0 spring I think) so not much fiddling required there.
thanks for the replies, I was able to see one in action last night at the track and I was impressed. I asked the guy what he thought of it and he told me the conrods were really weak. Other than that, it did look like a rocket