My wb has a twin system 2" then a single muffler like the wb statesman with twin inlets and outlets just near the rear axle on a bit of an angle to go up over the diff.
My Dad has a V12 which he has used 4 wb statesman mufflers to match the original quad system on his car, 2 near the diff and 2 right at the back with ss pipes welded to the 4 outlets on the mufflers, original exhaust was to expensive at $4200.