If you're sticking with bowden which I recommend for a little while, you should just get the metal replacement one in either the single or dual gear. I ran the single gear for a while but after doing some speed improvements I wanted the dual gear to prevent the slippage that felt like was happening.
Also you should probably replace the bowden in the hot end with capricorn, at least that portion. You can look up the Luke Hatfield/CHEP hot end fix, there's a good video by CHEP. Print all 3 sizes of the little washers before you take anything apart though. I stuck with the stock tube the rest of the way and the higher temp capricorn inside the hot end.