"v4" (blue part in the pictures) was already much tighter, than the (black) stock piece. But it was still not tight enough to print flexibles properly. The "v5" (depicted in copper) should tackle that now. More on the extruder: https://burningbecks.wordpress.com/2019/09/18/sanjiu-sanbrother-metal-bmg-extruder-aero-style/