Quote Originally Posted by Ryan351 View Post
Resurrecting an old thread but to Olivier 20, I'm looking to build my own as well. I have an 86 pro comp, and DAMN it is LOUD.
My question is how did you go about forming the downpipe?

Thanks and nice build.
Ryan
Hi mate ! Yeah our boats are definately really loud !! For our venturi exhaust system : we started by doing the left exhaust to the right exhaust connexion with the elbows , After that we used Hole Saw to make an exit hole in the middle of that 'L&R connexion'... For the downpipe, we took the rest of our aluminium pipe and cut one end with a Hole Saw to get a half-circle pipe end. We put that half-circle end over the exit hole on the ''L&R conexion'' and measure it down to the shaft level or propeller nuts. Then for the last part: the other end of the downpipe was machine press a bit , a cut at a 45 degree angle and weld up the downpipe to the L&R connexion with a little angle (eyes view angle that seem great for us,nothing scientific here !).

Take a look at the pics in the 1st post while reading my explanation... I'm french and my english is not the best in the business !

I hope i help or enlighten you a bit !!