Hi, Garland, sorry for delayed response, but we have been in the process of moving for the last two months. I just saw your message this evening. My engine hush box article was published in the March/April 2013 issue of Ocean Navigator magazine. It may be available online. If not, I can email the original text to you. Your engine installation manual will give you the required figures for intake and outlet. Size the airflow based on maximum sustained RPM to build in a safety margin. Harry

Hi Harry
I'd be interested in your design for a hush box, if the offer still exists!

Specifically, I'm most interested in the air intake and outlet design.

Thanks!
Garland Gray