Today I built a extra plenum for the Katran. It comes with one plenum from the factory. So I just copied the factory plenum doubling the plenum area. 
The unit on the left is the factory unit. The threads are assistant with removing the unit. It’s very easy to push the plenum out after removing the bottle. So i opted to for go threading the hole.
Here’s it with the regulator installed
Here’s the full valve Assembly. As you can see in the photo it leaves the Plenum much larger. This Katran is the high power model. I couldn’t add anymore plenum with modifying the tube that houses the regulator and plenums. Katran sure leaves a lot of room for more plenum but they need to machine the full length of the house. But as it is you can add 50mm more plenum.
I’m hoping to get this tuned shooting the 25gr jsb pellets in the 965 fps range and get a fairly lower regulator set point. This gun came with a regulator set point of 165bar. This works fine, but adding the plenum I’m targeting for a 145 bar set point and gain a bunch more shots per fill.
The unit on the left is the factory unit. The threads are assistant with removing the unit. It’s very easy to push the plenum out after removing the bottle. So i opted to for go threading the hole.
Here’s it with the regulator installed
Here’s the full valve Assembly. As you can see in the photo it leaves the Plenum much larger. This Katran is the high power model. I couldn’t add anymore plenum with modifying the tube that houses the regulator and plenums. Katran sure leaves a lot of room for more plenum but they need to machine the full length of the house. But as it is you can add 50mm more plenum.
I’m hoping to get this tuned shooting the 25gr jsb pellets in the 965 fps range and get a fairly lower regulator set point. This gun came with a regulator set point of 165bar. This works fine, but adding the plenum I’m targeting for a 145 bar set point and gain a bunch more shots per fill.
