Mark, funny you say that at BD are telling me the same, but the guy with the SC in WA I am talking with had his dyno tuned to get it running sweet after he changed the nose pulley, so maybe that simply entails adjusting the fuel rate into the pump. BD tell me the swap over process for mine is plug and play. I am still wondering about the whole 'timing of the pump' issue that seems to be an important part of the TD42 journey when a pump is changed.