Its not at all common, for one thing they were regularly paired with big block Chevrolets that put out 100 more ft lbs than just about any small block.
As far as the cat converter issue, in fresh water yes you will not have an issue. In salt water you eventually will. And just for sh!tz and giggles I priced out an OE Volvo system, close to
$3000 A SIDE!!!go over to
www.volvopentastore.comand take a look.
And unlike vehicles, where the cats are covered under a fed warrentee till 8 years or 80,000 miles, when they go on a boat you are SOL. I don't think you can just eliminate them.
I think I better hurry up and get a new outboard for my next boat (lol) before they put cats on them too.
Its bad enough if you lose an impeller, or pick up a bag with an exhaust system that can then it over 300 *F, a cat system (I've monitored cat function and temps on my 07 Jeep with an OBD-II scanner) runs much much hotter than that. In a closed engine compartment surrounded by fiberglass, with rubber fuel lines....
NO THANKS