I like how the Rcxp module makes a couple of my engines run. It has a bit more aggressive advance curve than the Rcexl units so acceleration is a bit more crisp if that makes any sense. The advance drops out nicely when throttled down so there are none of the Rcexl #4 type of issues. The spark is also noticeably brighter and louder when watching a plug inserted in the cap. As a result, starting seems a bit easier and I believe the engines tolerate a bit wider fuel / air mixture at all needle settings. Disclaimer here though ...... I have no real complaints about Rcexl ignitions unless they happen to be paired with one of the problem sensors that pop up from time to time.