I am pretty sure this is the "custom" barrel that comes stock on the EM1. If it is not, then forget this review because I am reviewing the barrel that came with my EM1. It shoots very nicely and doesn't break many balls. For $70 retail it is really good but it doesn't compare with a boomstick or an otp G-3. It is a very light barrel. It weighs next to nothing; I barely feel it in my hand.
It breaks balls sometimes but that's only when I shoot cheap balls.
For it's price, this is a great upgrade for spyder owners. It looks REALLY slick and shoots accurately with decent paintballs. It is not silent but it isn't loud either. I have the 12" and the porting only begins near the end of the barrel. Overall this is a really nice barrel and I reccomend.