When I start using my new Ender 3 I was not happy at all with the filament default path because of management and friction. I try to use the side arm ( https://www.thingiverse.com/thing:3568056 ) to arc the filament but it was still not enough to completely remove the friction on the extrusion motor. I searched for a solution and I find some with bearings but I did not have any at the time and the side arc path is not a great solution for me just because of space management. After all of this I end up by designing this mount to position the extruder on the top. This way you can have the spool directly connected to the extruder motor reducing friction and drag.
My first design was the 90° version but after testing I find it to apply too much pression on the tube. I prefer my last diagonal version because it has a nice angle for the tube to naturally curve without pression and also good angle for the filament spool when on top like mine.

The original tube should work. After some testing I recommend around 44cm of PTFE tube to allow it to freely move side to side in the X axis when at the bottom ( I only tested for my ender 3 with the extruder at the top center in the diagonal version mount ).
To mount the extruder on top the original cable did also work but for a better cable management I had to order a new longer cable. I ordered the cable "XH2.54 4pin/6pin Stepper Motor Connector Cable Extension" from ebay for about 2€ and with a length of 150cm to be on the safe side. After installing the cable it was a little longer than I needed but I just store the extra length inside the board case without any problem.

ATENTION! : don't forget to confirm the cable connections before powering the printer or you may burn your board driver if not connected correctly. In my case the original Ender 3 cable has the two middle cables switched ( photo in gallery ).

NOTE : the front and back holes are intended to use with T-Nuts, I use only the front one. The hole diameter is 6mm thus you may use M5 screw or smaller.

If you what to use my rail covers : https://www.thingiverse.com/thing:3829396

Other things I used or may be useful :
Spool holder : https://www.thingiverse.com/thing:3471434
Dust filter : https://www.thingiverse.com/thing:497764
Printed T-Nuts : https://www.thingiverse.com/thing:3510542

UPDATE :
I still use my original diagonal version without any problems but as requested I added a second screw hole in the back for better fixation.

Enjoy and post your makes!

If you found my Things useful, treat me to a cup of coffee :)