what pipe is it? Generally i always start between 11.5 and 12" then adjust for the best performance from there (IE high RPM but enough torque to hold through turns).


Id start at 12" then run the boat. If you have a tach it makes life much easier then going by pure sound. If the boat runs good at 12" and holds the RPM through the turns, start shortening it 1/8 at a time til its screaming down the straights, and just barely falls off in the turns, then lengthen the pipe back out to where it holds the R's through the turns.