Need gun doctor to drop fps on my GBB

[terrorist one]

hello folks, i am looking for a experience gun doctor who can somehow make my 2011 KWC mini uzi (Guarder version) shoot a little under 350 fps with .20.
The current FPS is around 410 with CO2 mags.



Getting the green gas vale is ot of the question since they are discontinued and the WA arms mags will not fit in the 2011 version.

What i am looking for is someone that will be able to machine something to lower my FPS.

Here is a picture of the loading nozzle to give you an idea of the work needed.



PM is best for communication.

Thank you for the help.