I ran the Murnan Modified Novarossi +4BTT this past Saturday. The engine felt awesome on the track. I ended up running the 9901 pipe with the short round novarossi header, 6.5 mm ventury, and c6tgc glowplug. With 1.0 springs on the stock MBX6 clutch, the engine had too much bottom end grunt for the buggy. I switched to .9 springs, and it was better. The weaker springs made the engine easier to drive out of the corners. Top end was brutal. I could have run over the other buggies if i wanted. The engine cleared the largest jumps with ease, and made 9+ minutes of runtime. I'm sure 10 minutes will not be a problem when it fully breaks in. The piston kept getting stuck at tdc on the starter box after 2 gallons of use, so it is definitely not fully run in yet. Temps were around 240 with a good amount of smoke. There is definitely more power, and mileage in the engine. This is one bad engine!