From what i hear you can't go wrong with any pipe such as the ribbed or the hpi dual chamber. Depends on what you want to do. I personally like the looks of the dual chamber one , i hear that the ribbed is really loud. If you are looking for bottom, get the ribbed. If its top speed u want, get the dual chamber. I'm getting a gh single stinger pipe for my new 247 pro motor for racing, suppose to give insane power. But their on backorder for the next month.