I have the X4 Labs extender, unfortunately X4 is out of business. I used the X4 base and rod set with my PMP head attachment. Used some tape to increase the diameter of the rods to fit the PMP attachment. Also X4 had various spring sets, I went up to the 4500 gram set, caused me blisters with the PMP, I wonder if that’s why Penimaster does not offer a higher load spring option?
I did a quick search and it looks like the Quickextender has spring options up to 4000 grams. You could purchase a set and see if they will fit in the PMP pistons. If not, you would need to find other springs that fit the PMP or purchase an entire base and piston system from someone such as Quickextender, not sure what springs the Quickextedner comes with.
Also, the non-contoured base of the PMP gave me terrible ball burn, so using the X4 base was a plus as I never experienced ball burn with it. Looks like Quickextender also uses a contoured base.
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