I've read here that pre-turbo jets which, based on OEM turbo housings, can only be installed further upstream (post-MAF) and not at the compressor should be installed to spray against the direction of oncoming air post MAF to atomize most effectively (basically spraying at the back of the MAF housing).
Based on my VW GTI's engine layout and more specifically the intake layout, I've been studying the air velocity in a 90 degree bend (the bend leading to the horizontal intake pipe running across the back of the engine (from the MAF to the beginning of the long straight).
Intake layout:
This video shows in yellow the highest velocity stream which would help atomize any water meth spraying inside of this intake pipe:
https://www.youtube.com/watch?v=OvprEu-yH-A
Based on the video example alone, should I install the jet at the top of the horizontal pipe to spray against (into) the yellow stream? Or at the bottom of the pipe to spray into (with) the yellow stream?
When people place jets within the intake tract, are they accounting for flow diagrams or streams?