If your motor is a.26?? your tune pipe is to long. You have to start cutting it down a 1/4 at a time to find that sweet spot. The tune pipe is like a booster/blower,these motor act like a motor cross bike. all of them have a power band that kicks in at the wright rpms. The nitro boats are the same,they have a power band too. The key is to have the wright tune pipe and the wright lenght to have that power band. I'm going to give you three links to help you understand this better. here two are prop info and sizes.[link]http://rcprops.com/TechNotes/rcprop_tech_info.htm[/link][link]http://www.xtremercboats.com/tech/propchart.htm[/link] The other is tune pipe info.[link]http://www.prestwich.ndirect.co.uk/tunedpipetheory2.htm[/link] these should help you out.