it works wonderfully, the cloud of CO2 is imperceptible
none at all
If you have an M98 the installation can be quite demanding. The vertical adapter you need is reeeally hard to screw in. The hoses aren't too hard to connect. But thats just for the M98. The expansion chamber itself is great, the design is very clever. The only time I'm able to see the cloud of CO2 coming out of the barrel is if its really dark. It helps out with shot consistency and air efficiency.
If you shoot CO2 and have some money to spend, get this. It looks great and it works as well as possible.