I've made the main bracket longer so that the spool is flush or in front of the rear of the printer, and relocated the guide-arm hole so as to reduce the sharpness of the bend that the PTFE tube has to make. I also flattened the top and bottom of the “spool roller” to make it easier to print, since it will be sitting on 608 bearings, this doens't affect performance. Make sure to use supports on the slotted areas of the main bracket, as well as under the spool roller ‘pin ends’…for some reason, the slicer doesn't create these automatically for me.