One of the first things I did to my trike was add a FL-VIED 10,set at 75. She ran OK,but it can be adjusted,and if it can,I will.
I noticed black soot from the right side muffler,none on the crossover/left side.So,since it can be adjusted and I want to tinker,I set it at 50.Didn't run like I wanted.Also paid no attention to the pipes.I then set it at 65 or 1/2 way between 50 and 75.Took it for a 20 mile ride,ran better than 50.This morning I noticed the right side muffler was clean and the left side was black.
Now...time for speculation and opinion.
PS:not done tinkering yet.