Here’s my take on solving the filament path / tension issue on my Ender 3. I noticed that some of my prints had diagonal lines on the top layers as the extruder was struggling to pull filament into the feed hole at a consistent pace. When there was tension, I got 10% or 15% under extrusion.

I came up with this design to address problems I found in mounting the other “2020” filament guide on my X gantry. The bungs broke almost immediately since I printed the parts in PLA. This version slides over the top of your spool holder (the metal part). Just un-screw one of the “nuts” holding the roller to the metal piece and slide this guide over top. It should be a tight fit, which keeps it from wobbling around. The straight part should rest on the top of your frame, making for a much smaller profile piece.

This part works great with an extruder intake guide like this one: https://www.thingiverse.com/thing:2873157