Those systems all overlap to some degree. What I found (the hard way) was that when primary main jets were reduced sufficiently, the engine runs noticibly lean when cruising over 60 mph. The way I learned this was after a dyno session where between two runs with different PMJs the power looked very similar. So I drove home with the leaner jets, because, why not? Well you can guess what happened. The engine revved and died. It wasn't a good road to change jets on, but doing 55 mph in the right lane was pretty much keeping with the flow, so I just drove it home.
