I am replacing the dry exhausts on my twin mirrored pair of Gardner 6L3B's on my 1965 G. De Vries Lentsch Jr built TSDMY. As part of this I am exploring the possibility of including a catalyst or some kind of particulate filter (DPF) into the new arrangement which also includes restoration of the funnel and mast back to its original 1965 incarnation (as per the pic). The engines will thus exhaust at a reasonably low air-draft height through a funnel which sits atop the original boat deck (as per the pic). The boat deck these days is used much more for general entertainment and therefore I seek to keep it as free as possible from smoke, particulates and noxious gases. Obviously I understand that back pressures can't be compromised. I'm most interested in whether anyone has done this before and if so, what was your approach? Please no-one try and talk me into a wet exhaust conversion. With regards to the Gensets they are a pair of new Cummins Onan MDKR17.5KVA Quietline Series again being directed dry up the stack and on to the boat deck. So X4 chimneys in all.