by scubarider2 » Mon Nov 23, 2015 11:30 am
I run a Rotax 912uls with Toucan double exhaust and have never had an issue. They stick out below the bottom cowling at least 6inches if not more. My firewall is well sealed with no issues there.
All I can recommend is to make sure you do not have any leaks inside the engine compartment and seal your firewall as well as you can. If you still have issues then extending your pipes might have to be your next step.
Dennis
Live as though you were going to die tomorrow, learn as though you were going to live forever...