I just finished expanding the draft on one of my Ropp Canadians (this one is 193mm long). The standard draft is 3.6mm, which isn't bad at all, but at 4mm it's just that little bit "more". Oddly enough I did think that 4.3mm was "too much" when I drilled an acrylic stem to that size for one of my cobs. Could have just been the way I was packing it, or maybe the button was too large...
Anyway.
For my first bowl in this particular Canadian it was a fantastic smoker and Mississippi River is as pleasant as ever.
(After sitting in a jar for a year now, while dipping into it every few months.)