To those having trouble with adequate fuel flow to their Moki with the BCM muffler, before you spend time and money and on a pump or regulator, simply try blocking off one of the exhaust outlets. My 2.1 runs great on 5% nitro fuel and STANDARD size fuel tubbing with one exhaust outlet blocked-off. I can get it slobbering rich (4-cycling) which by the way is a requirement for proper break-in during the initial runs.