Basic bone stock out of the box in .22 (velocity will vary from gun to gun but will give a starting point) RWS hobbie 11.9 gr. 481fps (some go as high as 550 out of the box)
Cleaned and lubed with barrel port and receiver port matched .170 transfer port seal installed 493fps
Bolt probe inlet drilled to .111 573fps shot count approx. 60
probe inlet and outlet drilled to 1/8 inch, 605fps shot count approx. 55
probe inlet drilled to .180 outlet drilled to .154 649fps shot count app. 50
the above numbers are with one cylinder shot count is for two cylinders
same as last with two cylinders 658fps ( using one cylinder seems to lower fps by 10 fps in most cases.)
wire bolt probe installed and two cylinders 689fps shot count approx. 40
open inlet of valve, taper head of valve, enlarge opening around head of valve in brass cap, taper end of pin and reduce head diameter of pin with bolt probe 705fps at 66 degrees shot count 35
as they say your results may vary