After about 10 years I put a tbt maxi Pro kit in mine along with a short stroke extension and I believe a sleeve made from a Carling can.
Fired 5 shots through it and it was sweet as honey and quiet. Then I put it over my chrone and was expecting mid 10 to mid 11ftlbs.
Just shy of 15ftlbs

with no power washers, never has a gun been disassembled so quick

.
I didn't want to change the originally spring so I collapsed the spring.
Now has about 10mm of preloaded and still shoots sweet but at low 11ftlbs.
On stripping i did find a washer id missed the first time so removing that helped.
On the whole id recommend a tbt kit and a chrono for all springer shooters.
My ntm tx200 will be getting one at some point.