I have recently upgraded my black star with an eaglevision kit and an Aussie parachute seal.
After a polish and an application of dri slide in the compression tube I reassembled the gun and chrono tested with rws superfield, the results were 530fps with 5+- fps.
The recoil was greatly reduced and the firing cycle was noticeably much faster, you wouldn’t even know it was the same gun.
Weihrauchs have been known to be greased with horrible grease but mine was completely dry and was going rusty on the spring and piston body.