I snagged my Berk Race from the for sale section here. 270$ plus shipping. Took 15 minutes to bolt on and I can revert back to stock when i want. Mine has the balancing tube, It's a bit louder, but not overly loud, at least with the stock dps and stock mids in place. Does have a nice whoosh at full throttle though. Overall I'm very happy with it.
2008 135i - FBO + JB4 15ohm + Water Meth