I decided to go with two seperate #8's seeing that the "Crossflow" is really just two straights welded together (actually flows better than a "True Crossflow").  If I need to, my muffler guy will weld them together himself and mount them behind the differential housing (as originally intended) if the exhaust space/routing allows, other than that they will stay along the driveshaft and exit in front of the rear tires.  For those interested, my order # was 3228: Street, 2" in, 2"out, straight configuration.  Mufflers are five trap configuration with overall dimensions of 3x5x16 each.

These mufflers flow 175+ cfm, equivalent to Borlas but are low and rumbly like three chamber Flowmaster's (cost MUCH  less) With the X-crossover in back of the trans tailshaft, the exhaust note is unique, VERY similar to 180 degree exhaust headers or a 60's Indy Race car.  Wav file of a V8 equiped Mustang with Rhino Mufflers and a Dr. Gas Synchronizing Crossover