two cents : I just contacted Ken as well. Looking into that option. He suggested re-milling or "top plate/gap modification" on the 131 to avoid future voice coil rub. Magnet recharge, etc. He also said that on the 131 after plate opening, it can be made into a K w the E re-cone as mentioned above by Tee Jay. I'm hoping I can make a lower volume K out of this. Loud isn't a problem here. Still more correspondence w Ken to do. Anyone ever pull off a softer yet still full sounding K this way before? I believe the D-131 is slightly less output than the D-120.