FWIW, I replace the wick in Lionel smoke units with shredded braided wick and also replace the 27 ohm resistor with a 20 ohm unit, I get plenty of smoke from most Lionel fan driven smoke units. It's possible to get very decent smoke from Lionel units, it's just easier to get good smoke from the MTH smoke unit.
While MTH has two smoke resistors, the actual power dissipated in the smoke unit is similar to Lionel smoke units, it just has a more effective delivery system to the wick in the form of sandwiching the wick between the two resistors. If you repack the Lionel smoke unit, replace the resistor (for 27 ohm units only!), and make sure the resistor is firmly in contact with the wick but NOT totally covered, you'll get very good smoke. For smoke units in TMCC with the voltage regulator, or any Legacy smoke units, DO NOT change the value of the resistor! The one exception is if you find a 6 ohm resistor in TMCC or early Legacy units with the voltage regulator, change that to an 8 ohm resistor, the regulator will have a longer life.
Some other tricks with the Lionel unit is enlarging the intake hole for the fan, and what I find equally important is enlarging the stack hole as much as possible. I also make sure the resistor is positioned near the stack hole, but in the airflow between the fan chamber and the stack. Finally, insure that there is a good clear path from the fan chamber exhaust, across the smoke resistor, and out the stack.
