Ignition timing advance/retard(ed?)question
 

I'd like to adjust my ignition timing, and as this is the beginning of an experiment, I'm wondering how many degrees advance would make a good 'test' to start with, something that I could drive safely on for a week or 2 while I get used to it.
recently there have been pretty big changes in the airflow and I really get the feeling that the timing is off. just to give you an idea, a big exhaust leak was fixed (EGR valve to header leak), new (much better with less restriction) exhaust was put in.
since all this happened, I've got a bit of a backfire and the power seems less.

here's the thing, I'm not sure whether the timing should be increased (decreased?). I know it is off but not sure by how much or in which direction. If these clues give anyone an idea of how it should be adjusted I'd be really happy. Thanks a lot!

I do not think I will mess with moving teeth in the AFM, I think I will stick with adjusting the timing

Pull the ECU fuse for a minute or two then replace it. Then drive the truck a few days to let the computer learn a bit about your setup.

Thanks abecedarian! I have read about resetting the ECU before but never thought of that in this case!
So, in this way, my truck could 'learn' the correct airflow, through the o2 sensor? So, I might not need to change the ignition timing at all? Thanks. I will do some more searching on ECU now too.