Yep, bad idea.
There are some sporties that do this, but if you look closely, the gen exhaust ties into the main exhaust right at the tailpipe exit and has a clamshell glassed in to keep the two flows separate. I still don't like those, but less risky. I think this system is responsible for some of the otherwise "unexplainable" water in genny engine events.
Run the exhausts separate.
Yep, bad idea.
There are some sporties that do this, but if you look closely, the gen exhaust ties into the main exhaust right at the tailpipe exit and has a clamshell glassed in to keep the two flows separate.
True on the big and medium Bertrams of my acquaintance. Worth bearing in mind that the genset(s) usually have water-lift mufflers which may prevent backflow.