Pipes are not specifically plane or marine pipes. Some manufacturer or retailer may call one or another a marine or airplane pipe for a particular application, but they can be interchanged.

There is a big difference in the types of pipes available though. There are rpm pipes, torque pipes, those looking to maximize high performance speed and power, those that look for a range of power at different rpms. I have used many different types in different types of boats depending on their racing needs.

For example the pipes with no flat area between the divergent cone and convergent cone are more peakier. They try to maximize rpm, power and speed, at the cost of low speed running and idle quality. I usuall use these pipes on my C and X hydros. They tend to run flat out with little throttle input.

Pipes with a flat center section tend to give more of a midrange of power, a little more torque, better idle, and a smoother range of acceleration. I tend to use these pipes on my offshore catamaran, and on my scale hydro. The cat needs more throttle input in the turns to keep it from flipping, yet I still want it to accelerate hard out of the turns. Scale racing often has very slow milling before the start of the race, and a pipe with better midrance will handle the slow milling and give quick acceleration when the rae finally starts. Where a peakier pipe might load up and stall when you finally give it gas.

The pipes with a little center section can still give you great top end, so it depends on the particular boat. If you have a boat you run flat out all the time, with little or no slow running go with a pipe with no flat center section. If you have a boat that needs to run both fast and slow but still have good acceleration, go with a pipe with some flat center section.

In the end it's the total combination that is the real key. Having the boats center of gravity in the right spot. Having a strong enging tuned properly, using the right prop, and having the right style pipe at the correct length all work together to make a boat run super fast. If any of these factors are way off it's never going to run right.

Also have a peakier pipe at the wrong length and the boat may not run at all. A pipe with more of a center section will be easier to get running so you can fine tune it.