Phillip, I've been watching your cowl development, we've been on the same path dealing with similar issues. I fixed the inlets and use 4" Scat to make the connection to the cht cooling ducts.

The last piece, as you mention is the cowl exit. My original design is adequate and extends just past the firewall. I'm also running dual exhaust and had added cuffs to prevent airflow back into the rear cowl. Just finished making a new bottom that I will bond to the lower cowl, it incorporates the exhaust cuffs, is deeper and extends farther aft.

Thanks for the tips. Good to hear what others are doing to address the cooling issues associated with the Jabiru engine.

Jake

Thanks Phil, 

Need to pull the wings and move it to my hangar, then it'll be a a couple weeks and it'll be back to its flyoff phase again... That was started a long time ago but it never got finished, so it'll be up to me!

Did I read that right? You donated yours?

Guy