I suppose everyone has their preferences, but I feel that pipe pressure is the only way to go. I have a jet that I bought second hand with fan pressure. I would have to set peak rpm on the ground with the transmitter knob at max lean. Then once in the air I'd have to turn the knob all the way rich and would end up not quite rich enough. After a dozen or so flights I converted it.

I have never had any of the alleged problems with pipe pressure, and have found it to be very reliable on all my DF's. What I like best is the range of authority pipe pressure provides. It goes all the way from too lean to too rich just by turning the transmitter knob. I never have to touch the mixture valve. Just start it up, a couple of clicks on the knob and go fly.

Anyway to answer your question I think just about anywhere on the wide portion of the pipe will do. I put mine about half way down the pipe. I used an Alumiweld rod to put a small boss or bead on the pipe, then drilled & tapped it for the pressure fitting. JB weld should also work.

Joe