I'm not sure if I can get the top of the riser that high. The limit is the counter (at sink height in this drawing - about the same of the cockpit sole). As that pipe is hot (and will need to be insulated to the injection elbow), I don't want to crowd any flammables. I'd like to go (safely) without a vented loop.

As far as the height of the muffler, raising it -perhaps with a platform- may help access(I straddle the engine/transmission when sitting inside the cockpit manhole). I know they want a minimum distance between the top of the riser and the muffler, for heat reasons.

Did you use a Volvo injection elbow or supply one on Tortuga? Can you build a suitable injection elbow with a T, reducer and plumb in your own injection point or is a stock (like the Hamilton injection elbow) the best way to go?

Thanks.