I visit another forum where the OWB's are discussed a lot. Someone mentioned that CB has redesigned the combustion chamber. I guess you simply remove the refractory brick that stands on edge in the fusion chamber and replace it with one that has a half-moon shape. At the same time you completely remove the refractory panel that lines the floor of the firebox and that holds the grates in place. I've read that the OWB's burn much cleaner with better efficiency. Also, most of their OWB had welded panels with holes drilled through them for the primary air flow into the firebox. I've been told they have a retro kit available for some models where the welded panels are removed and replaced with removable air panels (I believe they older style E-Classic 2300 is one of them). Any of you other CB E-Classic owners heard anything about this? When I get time I want to call my CB dealer and see what he has to offer. Thanks, Roger