...after having the Impreza fpr installed on my car for over 4 weeks and doing some wot runs today:
For comparison, I took a pic of the tip on my wife's stock '02 Lancer ES:
While my tips have more visible soot in them, modded turbo'd cars (WRXs, Evo's, SRT-4's) running afr's in the 12:1-11:1 range normally have the stuff caked on in there...
-Chike