The 2.1 version of the Duplicator i3 actually comes with most of the mod's I did to my printer. The thumb screws, D4 extruder gear, belt rubbing fix etc. The only thing I might suggest is looking at a better cooling fan setup. Thingiverse has lots of options. I currently have the DiiiCooler. It cool well, maybe too well. My biggest gripe about it is that it's much harder to see what the nozzle is doing. I may try one that mounts on the backside like this.