No most engines are specific to the tune they want. I have seen people have a base line to start at from the center of the piston to the center of the taper of the pipe. But this is what changes the pipes performance on engines in general. The shape of the pipe as well as the length of the header and the length of the pipe. And the standard lengths that I have seen have been on marine engines and they to also very from manufacture to manufacture. When the pipe is longer meaning the chamber not the header length general rule of thumb will be more lower end torque and power when the shorter the chamber the more top you will gain. But like I said before this is a rule of thumb the engines do react different at times to all the variables.