I have a Zenith CH750/Jabiru 3300 and the exhaust system is very leaky at the slip joints where the 3 headers on each side meet the muffler's sockets. The slip joints aren't the tightest and due to backpressure, most sealants burn/blow out. Compounding the problem is that there really isn't enough room on the muffler side of the joint to wrap, clamp, band, etc. any sort of overlapping material to attempt to seal the joint.
Why's a CH750 owner asking a Sonex question?
I understand that the usual Jabiru 3300 installation in a Sonex utilizes straight exhaust pipes rather than a muffler. Seems like that should provide very minimal back-pressure on the 3-into-1 collector. The muffler on the CH750 installation seems very restrictive and probably produces a lot of back-pressure. Are the Sonex's slip joints very leaky? Just wondering if reducing back-pressure on my 750's exhaust system would help cut down on leaks or help keep sealant in the slip joints!