Aaaaarrrrrggghh, not this again!
Paul's correct, volumizers do sweet f.a. other than making Angels look even cooler as far as many owners are concerned. OK, they save a tech a second or two in getting into the LPR, etc 'cause you don't have to use an allen key to remove it, but that's it.
Don't believe me? Go ask John Rice, he's only the guy who designed the Angel so he might just know a tiny little bit about them.
The volumizer apparently appeared because somebody saw one of the early Angel prototypes fitted with an external LPR adjuster, which just happened to be a short cylinder running parallel to the barrel - in other words, just like a volumizer. This 'somebody' didn't know what the adjuster was and came up with their best guess.
The volumizer is just a cosmetic gimmick and the only performance benefit it provides is to the manufacturers/vendors profits.
If you want better consistency from an Angel, simply make sure it's tuned correctly, use good paint with a matching barrel and don't drink too much the night before.