I agree, afterburner is not a option, to expensive to purchase and operate, just getting the stack temp down would help i think. Converter may get gummed up in a short period of time, maybe build a scrubber of some sort with a water mister, would be cheap to operate but maybe a little messy to clean the misting chamber. no pressured to do something like this just thinking if I could figure a way so I don't alarm the neighborhood would be great, if I have allot to roast, I usually do it at night and if I'm lucky theirs a nice breeze. just roast for family and friends about 100# a month, nothing more then a hobby, never want to go commercial, to much fun staying tiny.
Rich