The new Osprey stainless steel B58 decat downpipe is exactly the same as our 5'' Super Sports Cat but without the 200 cell cat so there is no restriction in this pipe at all. The 5'' body section reduces down to a 4'' flex joint and tapers down again to the 80mm outlet to allow maximum flow and compatibility with a stock exhaust system. This is the ideal downpipe when power is the top priority for your B58.