Eric,

A tuned pipe is TUNED to boost the engine's performance, while it is running within a certain RPM range.
Mostly, it is tuned to give its boost at full throttle, maximum RPM.

When you throttle the engine up, it will reach a point where there will be a "step" in the power. The RPM will increase, at that point by anything from a few hundred, to a few thousand RPM, depending on the engine, the application and the pipe.

In most cases, this will occur, advancing from 70% throttle to 100%; breaking from the idle/low speed fuel circuit, to the full load, high RPM fuel circuit, which must be adjusted accordingly.

Please note; the engine cannot be run steadily in the middle of that range. If it "jumps" from 12,000 to 14,000 RPM, the engine cannot be operated at any RPM between these numbers; 13,000 RPM f.e., unless the tuned pipe is removed.

What pipe do you intend to use?