YS .45 Pump and 40 shrike?
 

What is the recomended length in the tuned pipe from the center of the plug to the expansion chamber on a YS .45 pump with tuned pipe. I almost have this one built but the length puzzels me on a airplane engine. On a boat I race in the IMBPA with a CMB .45 the length is around 10 3/4 inches, is this the same with a airplane engine with a tuned pipe? I will be running 15% omega in the engine if that helps.

Any help welcomed,

Thanks,
Brian M.