I get about 40 more feet out of it than my stock hopup. It is a litle tricky to put together and understand how it works. but i like it because I run .30's with a 540 fps gun and the hopup is almost all the way off, compared to my stock one where its about 1/2 way full.
Its very accurate, expecially with my barrel. However i do recall someone saying they revised the chamber recently.