I have been using this on a Spyder Xtra with a dead on drop forward, 48/3000 psi tank, J&J Ceramic barrel, this expansion chamber, Delrin ACS bolt, and a revolution hopper with the X-board.
Very consistant, works great with CO2 or Compressed air, perfect size and grip
None that I have noticed
I have been paintballing for about a year now and have made multipkle upgrades on my Xtra. Right after I got the gun, I started chopping paint, so I immediately went for the Delrin ACS bolt. I still chopped about 1/4 of the balls I shot, so I went with a new barrel. I 'upgraded' (not really an upgrade after I saw the performance of it) to a Smart Parts progressive barrel and was still chopping paint. I finally got a J&J ceramic barrel and have fallen in love with it. I noticed that my shooting was very inconsistant, so I began looking at expansion chambers. I found this sub zero at the local drop zone for $30, so I went with it. I bought it a week ago and have played at least five times with it. I have had no problems since. No more chopped paint, no more velocity spikes, but it has done wonders to the accuracy of my crappy mechanical marker!
This expansion chamber has done wonders to my entire game and I recommend that if you have the money ($30-40) to not hesitate and buy the sub zero...TODAY!!!