I built my offset about a year ago now and i use one of the online calculators for the build and every thing turned out good all but the exhaust. The calculator said I needed 80" of 2.5 pipe so I made 4 pipes 20" and it gave me way to much draft pulls ash in to the cc and uses way to much wood. So I've been putting a coffee can over two of the pipes as a damper and works great. So I was thinking (with can be a bad thing) that if I moved two of the pipes to the same side as the fb and dropped in a plate 7/8 the length of the fb and put dampers in the pipes I could use it as a offset or a reverse.