I'd hold off on thinking there's anything wrong with your exhaust
system just because some diesel mechanic makes a comment about not using a "lift canister." (admittedly, I can't envision what a Lift Canister is, and whether mine's got one)....but I'm going to find out now !
I had a "diesel mechanic" look at my 5411 and transmission in my Newport 27 when I first got it last Fall, and exclaim how I was due for a breakdown first time out, but when prodded, admitted he didn't really have that much 5411 background....and it's been solid as a rock for over a year now, and with the crappy wind we often have on the Chesapeake, I've ended up motoring probably 100 miles just this season, with no problems.
On top of that, as I absorb info on the net, I find that individual manufacturers installed things very much their own way in many cases, particularly involving the 5411, so what was "normal" on a Newport is maybe "oddball" or completely wrong if you used a Catalina or somebody else as your standard of how something should be.
I also remember reading one new Newport owner who was ready to tear apart his entire rudder and build one from scratch just because he was convinced the heavy tiller-torque he was fighting while under power indicated something terribly wrong with his rudder...while many owners replied back No, No, that's totally normal (as it also is on mine)....
So best thing would be to share some good pictures of how yours is set up, with another Newport owner, and see whether they're the same or not....keep it "apples to apples" before judging something's wrong with yours.
I say that because, from the sound of it, yours is just like mine.
I'll take some pictures.